Patent Application
20160272937
Descried herein are methods and compositions related to production of intermediate mesoderm cells from pluripotent stem cells. The techniques described herein find use in regenerative medicine applications.
Chronic kidney disease (“CKD”) is a significant global public health problem and is the leading risk factor for cardiovascular disease. In spite of advances in the quality of dialysis therapy, patients with CKD experience significant morbidity and mortality and reduced quality of life. For selected patients, kidney transplantation is an alternative renal replacement therapy to dialysis; however, this option is limited by the shortage of compatible organs and requires the use of lifelong immunosuppressive medication to prevent graft rejection. For these reasons, research in regenerative medicine, with the ultimate aim of generating functional replacement kidney tissue or even a whole kidney from a patient's own tissue, offers the potential for new therapeutic strategies to treat CKD and end stage renal disease (“ESRD”). Human pluripotent stem cells (“hPSCs”) have the revolutionary potential to generate functional cells and tissues for purposes of regenerative medicine and disease modeling. Both human embryonic stem cells (“hESCs”) and human induced pluripotent stem cells (“hiPSCs”), which are each members of the broader category of human pluripotent stem cells (“hPSCs”), possess the ability to self-renew and to differentiate into cells from all three germ layers of the embryo. This plasticity of hPSCs makes them an ideal resource for generating cells of the kidney lineage.
While other organs such as the heart, liver, pancreas, and central nervous system have benefited from more established differentiation protocols for deriving their functional cell types from hPSCs, considerably fewer methods have been developed to effect kidney differentiation. This may be partly explained by the complex architecture of the kidney and its functional units, nephrons, which are comprised of highly specialized epithelial cell types, such as glomerular podocytes, proximal tubular epithelial cells, cells of the thick and thin limbs of the loop of Henle, distal convoluted tubule and collecting duct cells. Thus, there is a great need in the art to establish a system capable of differentiating hPSCs into these nephrontic cell populations, further including establishment of protocols for generating nephron progenitor cell populations. Nephron cell progenitors, such as intermediate mesoderm (“IM”) and the metanephric mesenchyme, which can offer a common starting platform for derivation of specific kidney lineage cells.
Described herein is a simple, efficient, and highly reproducible system to induce IM differentiation in hESCs and hiPSCs under chemically defined, monolayer culture conditions. Chemical induction with the potent small molecule inhibitor of GSK3β, CHIR99021 (“CHIR”), robustly and rapidly differentiates hPSCs to a multipotent mesendoderm stage in a manner that recapitulates mesendoderm formation in the developing embryo. Further, hPSCs treated with CHIR can preferentially differentiate into lateral plate mesoderm, but with precisely timed addition of specific growth factors, this default fate can be diverted into definitive endoderm or other types of mesoderm. Importantly, treatment with CHIR, and the combination of FGF2 and retinoic acid (“RA”) effectively generates IM cells co-expressing PAX2 and LHX1 within 3 days of differentiation. This is the most efficient method to generate PAX2+LHX1+IM cells and the first demonstration of the role of FGF signaling as a potent inducer of IM-specific PAX2 expression in differentiating hPSCs. These PAX2+LHX1+ cells form tubular structures which express apical cilia and markers of proximal tubular epithelial cells and integrate into mouse embryonic kidney explant cultures, demonstrating their capacity to give rise to IM derivatives. In addition, PAX2+LHX1+ cells can also be specifically differentiated into cells expressing SIX2, SALL1, and WT1, markers of the multipotent nephron progenitor cells of the cap mesenchyme (CM), further demonstrating their capacity to give rise to IM derivatives.
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Described herein is a method for generating a mesoderm cell, including providing a quantity of human pluripotent stem cells (“hPSCs”), and culturing the hPSCs in a serum-free media including at least one induction molecule, wherein the at least one induction molecule is capable of generating at least one mesoderm cell. In some embodiments, the human pluripotent stem cells are human embryonic stem cells (“hESCs”). In some embodiments, the human pluripotent stem cells are human induced pluripotent stem cells (“hiPSCs”). In other embodiments, the at least mesoderm cell is an intermediate mesoderm cell. In other embodiments, the intermediate mesoderm cell expresses paired box-2 (“PAX2”), LIM homeobox-1 (“LHX”), and/or Wilms tumor-1 (“WT1”). In other embodiments, the at least one induction molecule is a Glycogen synthase kinase-3 beta (“GSK3β”) inhibitor. In other embodiments, the GSK3β inhibitor is CHIR99021. In other embodiments, the hPSCs are cultured in a serum-free media comprising at least one induction molecule for about 12, 24, 36, or 48 hours. In certain embodiments, the method includes further culturing of the at least one mesoderm cell in the presence of at least one growth factor. In other embodiments, the at least one growth factor includes fibroblast growth factor-2 (“FGF2”) and/or retinoic acid (“RA”). In other embodiments, the method includes further culturing of the at least one mesoderm cell in the presence of FGF2 and/or RA is for about 36, 48, 60, or 72 hours. In other embodiments, the method includes further culturing in the presence of fibroblast growth factor-9 (“FGF9”) and/or activin A.
Also described herein is a composition of at least one mesoderm cell generated by a method for generating a mesoderm cell, including providing a quantity of human pluripotent stem cells (“hPSCs”), and culturing the hPSCs in a serum-free media including at least one induction molecule, wherein the at least one induction molecule is capable of generating at least one mesoderm cell. Also decribed herein is a a pharmaceutical composition, including at least one mesoderm cell generated by the method for generating a mesoderm cell, including providing a quantity of human pluripotent stem cells (“hPSCs”), and culturing the hPSCs in a serum-free media including at least one induction molecule, wherein the at least one induction molecule is capable of generating at least one mesoderm cell, and a pharmaceutically acceptable carrier.
Also described herein is a composition of at least one mesenchyme cell generated by the method of for generating a mesoderm cell, including providing a quantity of human pluripotent stem cells (“hPSCs”), and culturing the hPSCs in a serum-free media including at least one induction molecule, wherein the at least one induction molecule is capable of generating at least one mesoderm cell. In other embodiments, the further culturing is in the presence of fibroblast growth factor-9 (“FGF9”) and/or activin A.
Also described herein is an efficient method for generating intermediate mesoderm cells, including providing a quantity of human pluripotent stem cells (“hPSCs”), culturing the hPSCs in a serum-free media comprising CHIR99021 for about 12, 24, 36, or 48 hours, and further culturing in the presence of fibroblast growth factor-2 (“FGF2”) and/or retinoic acid (“RA”) for about 36, 48, 60, or 72 hours, wherein the culturing and further culturing generating intermediate mesoderm cells that express paired box-2 (“PAX2”) and LIM homeobox-1 (“LHX”). In certain embodiments, the method includes further culturing in the presence of fibroblast growth factor-9 (“FGF9”) and/or activin A. In various embodiments, the method generates at least 50%, 60, 70% or more intermediate mesoderm cells.
All references cited herein are incorporated by reference in their entirety as though fully set forth. Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Allen et al., Remington: The Science and Practice of Pharmacy 22nd ed., Pharmaceutical Press (Sep. 15, 2012); Hornyak et al., Introduction to Nanoscience and Nanotechnology, CRC Press (2008); Singleton and Sainsbury, Dictionary of Microbiology and Molecular Biology 3rd ed., revised ed., J. Wiley & Sons (New York, N.Y. 2006); Smith, March's Advanced Organic Chemistry Reactions, Mechanisms and Structure 7th ed., J. Wiley & Sons (New York, N.Y. 2013); Singleton, Dictionary of DNA and Genome Technology 3rd ed., Wiley-Blackwell (Nov. 28, 2012); and Green and Sambrook, Molecular Cloning: A Laboratory Manual 4th ed., Cold Spring Harbor Laboratory Press (Cold Spring Harbor, N.Y. 2012), provide one skilled in the art with a general guide to many of the terms used in the present application. For references on how to prepare antibodies, see Greenfield, Antibodies A Laboratory Manual 2nd ed., Cold Spring Harbor Press (Cold Spring Harbor N.Y., 2013); Köhler and Milstein, Derivation of specific antibody-producing tissue culture and tumor lines by cell fusion, Eur. J. Immunol. 1976 Jul., 6(7):511-9; Queen and Selick, Humanized immunoglobulins, U.S. Pat. No. 5,585,089 (1996 December); and Riechmann et al., Reshaping human antibodies for therapy, Nature 1988 Mar. 24, 332(6162):323-7.
One skilled in the art will recognize many methods and materials similar or equivalent to those described herein, which could be used in the practice of the present invention. Indeed, the present invention is in no way limited to the methods and materials described. For purposes of the present invention, the following terms are defined below.
As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
As described, few methods have been developed to effect kidney differentiation. While a number of studies have attempted to differentiate mouse ESCs into kidney cells, only a few studies have reported protocols in human ESCs and iPSCs. These previous reports have produced cells which share characteristics expected of human kidney progenitor or epithelial cells. However, the identity of these differentiated cells have yet to be conclusively verified. In addition, the efficiencies of these protocols for generating cells of the renal lineage are low, necessitating the use of cell sorting to enrich populations of cells using markers which are not entirely specific to the kidney. For example, OSR1, a marker used to label cells of the intermediate mesoderm, is also expressed in lateral plate mesoderm, which gives rise during embryonic development to the adult heart, hematopoietic system, and vasculature. Other markers, such as AQP1+ of proximal tubular-like cells, have been suggested, but this marker is expressed not only in the kidney, but also broadly in the gastrointestinal system, lungs, and blood cells. For both markers, sorted cells are heterogeneous and include only a small percentage of cells that exhibited properties and behaviors of cells of the kidney lineage. While existing studies have suggested a role for Wnt, activin, BMP, and retinoic acid signaling in the induction of cells of the kidney lineage, inductive effects of other signaling pathways, such as FGF signaling, on kidney differentiation from hPSCs have not been reported.
Described herein is a method using sequential treatment of CHIR99021 and FGF2 and RA that induces efficient differentiation of hPSCs into PAX2+LHX1+ intermediate mesoderm. The method achieves efficient IM differentiation within 3 days, which is considerably quicker than existing protocols while still maintaining a high level of efficiency. The method is extensible to multiple hESC and hiPSC lines, and importantly, without the need to resort to flow sorting. The resulting PAX2+LHX1+ cells, are capable of autonomous WT1 expression—a later marker of IM differentiation. With the addition of FGF9 and activin, PAX2+LHX1+ cells specifically differentiated into cells expressing SIX2, SALL1, and WT1, markers of cap mesenchyme nephron progenitor cells. Cells generated by the described methods are further capable of forming polarized, ciliated tubular structures express markers of kidney proximal tubular cells and integrate into mouse metanephric cultures. The establishment of this system will facilitate and improve the directed differentiation of hPSCs into cells of the kidney lineage for the purposes of bioengineering kidney tissue and iPS cell disease modeling.
Described herein is a method for generating a mesoderm cell, including providing a quantity of human pluripotent stem cells (“hPSCs”), and culturing the hPSCs in a serum-free media comprising at least one induction molecule, wherein the at least one induction molecule is capable of generating at least one mesoderm cell. In another embodiment, the human pluripotent stem cells are human embryonic stem cell (“hESCs”). In another embodiment, the human pluripotent stem cells are human induced pluripotent stem cells (“hiPSCs”). In another embodiment, the mesoderm cell is an intermediate mesoderm cell. In another embodiment, the intermediate mesoderm cell expresses paired box-2 (“PAX2”), LIM homeobox-1 (“LHX”), and/or Wilms tumor-1 (“WT1”). In another embodiment, the at least one induction molecule is wingless-type MMTV integration site family, member 3A (“WNT3a”) or activin A. In another embodiment, the at least one induction molecule is a Glycogen synthase kinase-3 beta (“GSK3β”) inhibitor. In another embodiment, the GSK3β inhibitor is CHIR99021. In various embodiments, the concentration of CHIR99021 is about 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 μM or more. In various embodiments, the concentration of CHIR99021 is about 5 μM. In another embodiment, the hPSCs are cultured in a serum-free media comprising at least one induction molecule for about 12, 24, 36, or 48 hours. In an alternative embodiment, the method includes further culturing of the at least one mesoderm cell in the presence of at least one growth factor. In another embodiment, the at least one growth factor comprises fibroblast growth factor-2 (“FGF2”) and/or retinoic acid (“RA”). In some embodiments, the concentration of FGF2 is about 25, 50, 75, 100, 125, 150, 175, 200 or more ng/mL. In some embodiments, the concentration of FGF2 is about 100 ng/mL. In another embodiment, the concentration of RA is about 0.1, 0.25, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 μM or more. In another embodiment, the concentration of RA is about 1 μM. In another embodiment, further culturing of the at least one mesoderm cell is in the presence of FGF2 and/or RA is for about 36, 48, 60, or 72 hours. In various embodiments, the method does not include the use of a feeder layer.
Further described herein is a composition of at least one mesoderm cell generated by the described method of providing a quantity of hPSCs, and culturing the hPSCs in a serum-free media including at least one induction molecule. Further described herein is a pharmaceutical composition of at least one mesoderm cell generated by the descried method and a pharmaceutically acceptable carrier.
In alternative embodiments, the intermediate mesodermal cells are further cultured to generate metanephric mesenchyme. In various embodiments, the method includes additional culturing of the at least one intermediate mesoderm cell in the presence of at least one further growth factor. In another embodiment, the at least one further growth factor comprises fibroblast growth factor-9 (“FGF9”) and/or activin A. In another embodiment, the concentration of FGF9 is about 25, 50, 75, 100, 125, 150, 175, 200, 300 or more ng/mL. In another embodiment, the concentration of activin A is about 5, 10, 15, 25, 50, 75, 100 or more ng/mL. In another embodiment, further culturing of the at least one mesoderm cell is in the presence of FGF9 and/or activin A is for about 24, 36, 48, 60, 72, 84, or 96 hours. In another embodiment, the at least one intermediate mesoderm cell is a cell that expresses express paired box-2 (“PAX2”) and/or LIM homeobox-1 (“LHX”).
In alternative embodiments, the intermediate mesodermal cells are further cultured to generate a nephrotic cell. In various embodiments, the nephrotic cell expresses Lotus tetragonolobus lectin (“LTL”), kidney-specific protein (“KSP”), and/or the ciliary protein polycystin-2 (“CPP-2”). In alternative embodiments, the nephrotic cell expresses six2 homeobox (“SIX2”), aquaporin-1 or -2 (“AQP1”, “AQP2”), megalin,uromodulin (“UMOD”) In various embodiment, the nephrotic cells possess ciliary structures and/or tubular morphology.
Also described herein is an efficient method for generating intermediate mesoderm cells, including providing a quantity of human pluripotent stem cells (“hPSCs”), and culturing the hPSCs in a serum-free media comprising CHIR99021 for about 12, 24, 36, or 48 hours, and further culturing in the presence of fibroblast growth factor-2 (“FGF2”) and/or retinoic acid (“RA”) for about 36, 48, 60, or 72 hours, wherein the culturing and further culturing generating intermediate mesoderm cells that express paired box-2 (“PAX2”) and LIM homeobox-1 (“LHX”). In various embodiments, the concentration of CHIR99021 is about 5 μM, the concentration of FGF2 is about 100 ng/mL, and the concentration of RA is about 1 μM. In another embodiment, the method generates at least 50%, 60, 70% or more intermediate mesoderm cells.
In addition, described herein is a method for generating a mesoendoderm cell, including providing a quantity of human pluripotent stem cells (“hPSCs”), and culturing the hPSCs in a serum-free media comprising at least one induction molecule, wherein the at least one induction molecule is capable of generating at least one mesoendoderm cell. In another embodiment, the human pluripotent stem cells are human embryonic stem cell (“hESCs”). In another embodiment, the human pluripotent stem cells are human induced pluripotent stem cells (“hiPSCs”). In another embodiment, the mesoendoderm cell is capable of differentiating into an mesoderm or endoderm cell. In another embodiment, the mesoendoderm cell expresses BRACHYURY.
In another embodiment, the mesoendoderm cell is capable of forming a definitive endoderm cell. In another embodiment, the definitive endoderm cell expresses sry homology box-17 (“SOX17”). In various embodiment, the mesoderm cell does not express sry homology box-1 (“SOX1”) and/or or paired box-2 (“PAX6”)
In another embodiment, the mesoenderm cell is capable of forming a mesoderm cell. In another embodiment, the mesoderm cell expresses forkheadbox-1 (“FOXF1”), kinase domain receptor (“KDR”), t-box-6 (“TBX6”), and/or paired box-2 (“PAX2”). In various embodiment, the mesoderm cell does not express sry homology box-1 (“SOX1”) and/or paired box-2 (“PAX6”)
In another embodiment, the mesoendoderm cell is capable of forming an intermediate mesoderm cell. In another embodiment, the intermediate mesoderm cell expresses paired box-2 (“PAX2”), LIM homeobox-1 (“LHX”), and/or Wilms tumor-1 (“WT1”). In another embodiment, the at least one induction molecule is wingless-type MMTV integration site family, member 3A (“WNT3a”) or activin A. In another embodiment, the at least one induction molecule is a Glycogen synthase kinase-3 beta (“GSK3β”) inhibitor. In another embodiment, the GSK3β inhibitor is CHIR99021. In various embodiments, the concentration of CHIR99021 is about 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 μM or more. In various embodiments, the concentration of CHIR99021 is about 5 μM. In another embodiment, the hPSCs are cultured in a serum-free media comprising at least one induction molecule for about 12, 24, 36, or 48 hours. In an alternative embodiment, the method includes further culturing of the at least one mesoderm cell in the presence of at least one growth factor. In another embodiment, the at least one growth factor comprises fibroblast growth factor-2 (“FGF2”) and/or retinoic acid (“RA”). In some embodiments, the concentration of FGF2 is about 25, 50, 75, 100, 125, 150, 175, 200 or more ng/mL. In some embodiments, the concentration of FGF2 is about 100 ng/mL. In another embodiment, the concentration of RA is about 0.1, 0.25, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 μM or more. In another embodiment, the concentration of RA is about 1 μM. In another embodiment, further culturing of the at least one mesoderm cell is in the presence of FGF2 and/or RA is for about 36, 48, 60, or 72 hours. In various embodiments, the method does not include the use of a feeder layer.
In another embodiment, the intermediate mesoderm cell is capable of forming metanephric mesenchyme. In another embodiment, the metanephric mesenchyme expresses (“PAX2”), LIM homeobox-1 (“LHX”), Wilms tumor-1 (“WT1”), and/or six2 homeobox (“SIX2”). In another embodiment, the at least one induction molecule is WNT3a or activin A. In another embodiment, the at least one induction molecule is a Glycogen synthase kinase-3 beta (“GSK3β”) inhibitor. In another embodiment, the GSK3β inhibitor is CHIR99021. In another embodiment, the hPSCs are cultured in a serum-free media comprising at least one induction molecule for about 12, 24, 36, or 48 hours. In an alternative embodiment, the method includes further culturing of the at least one mesoderm cell in the presence of at least one growth factor. In another embodiment, the at least one growth factor comprises fibroblast growth factor-2 (“FGF2”) and/or retinoic acid (“RA”). In another embodiment, further culturing of the at least one mesoderm cell is in the presence of FGF2 and/or RA is for about 36, 48, 60, or 72 hours. In an alternative embodiment, the method includes additional culturing of the at least one intermediate mesoderm cell in the presence of at least one further growth factor. In another embodiment, the at least one further growth factor comprises fibroblast growth factor-9 (“FGF9”) and/or activin A. In another embodiment, the concentration of FGF9 is about 25, 50, 75, 100, 125, 150, 175, 200, 300 or more ng/mL. In another embodiment, the concentration of activin A is about 5, 10, 15, 25, 50, 75, 100 or more ng/mL. In another embodiment, further culturing of the at least one mesoderm cell is in the presence of FGF9 and/or activin A is for about 24, 36, 48, 60, 72, 84, or 96 hours. In another embodiment, the at least one intermediate mesoderm cell is a cell that expresses express paired box-2 (“PAX2”) and/or LIM homeobox-1 (“LHX”). In various embodiments, the method does not include the use of a feeder layer.
For generation of human iPS cells, BJ (ATCC) and HDFalpha (Invitrogen) fibroblasts can be reprogrammed by two rounds of overnight transduction with pMIG retroviruses for OCT4, SOX2, KLF4, and c-MYC (Addgene) produced in 293FT cells (Invitrogen). Human embryonic stem cell lines, H1, H9, and CHB8-H2B-GFP hESCs (passages 30-50), as well as BJ and HDF iPSCs (passages 12-40) can be cultured on irradiated mouse embryonic fibroblasts (GlobalStem) in DMEM/F12 (Invitrogen) supplemented with 20% KnockOut serum replacement (Invitrogen), 1 mM nonessential amino acids (Invitrogen), 2 mM Glutamax (Invitrogen), 0.55 mM 2-mercaptoethanol (Invitrogen), penicillin/streptomycin (Invitrogen), and 10 ng/mL recombinant human bFGF/FGF2 (Invitrogen).
Cells can be passaged using Collagenase Type IV (STEMCELL Technologies) at a 1:3 split ratio every 5-7 d. For feeder-free culture, hESCs previously grown on MEFs are initially passaged using Collagenase Type IV onto plates coated with Geltrex hESC-qualified reduced growth factor basement membrane matrix (Invitrogen) according to manufacturer's instructions and cultured in either mTeSR1 medium (STEMCELL Technologies) supplemented with penicillin/streptomycin or ReproFF2 medium (ReproCELL) supplemented with FGF2.
For differentiation experiments, hESCs or hiPSCs can be grown on Geltrex, washed once with PBS and dissociated into single cells with Accutase (STEMCELL Technologies). Cells are plated at a density of 4×104 cells/cm2 onto Geltrex-coated plates in mTeSR1 medium supplemented with the ROCK inhibitor Y27632 10 μM (Stemgent). Cells are fed daily with mTeSR1 without Y27632 for 2-3 days until they reached 50% confluency.
Mesendoderm differentiation—the media is changed to Advanced RPMI (A-RPMI, Invitrogen) supplemented with 1×L-glutamax and 1× penicillin/streptomycin and either CHIR99021 (CHIR, Stemgent), human Wnt3a (R&D systems), and/or human activin A (R&D systems) at the doses described.
Definitive endoderm differentiation—cells are treated with A-RPMI+1×L-glu+1×P/S+5 μM CHIR for 24 hours, then A-RPMI+1×Lglu+1×P/S+100 ng/mL of activin A for 2-3 days.
Hepatic differentiation—cells at the definitive endoderm stage are treated with A-RPMI+1×L-glu+1×P/S+1×B27 supplement (Invitrogen)+20 ng/mL BMP-4 (R&D systems)+10 ng/mL FGF2 (Invitrogen) for 5 days, then A-RPMI+1×L-glu+1×P/S+1×B27+10 ng/mL HGF for 5 days, then HCM Hepatocyte Culture Medium (Lonza) supplemented with 20 ng/mL Oncostatin M and 10 ng/mL HGF (Peprotech) for 5 days.
Pancreatic differentiation—cells at the definitive endoderm stage are treated with DMEM/F12+2% FBS (Hyclone)+50 ng/mL FGF7 (R&D systems) for 2 days, then high-glucose DMEM (Mediatech)+1% B27+2 μM retinoic acid (Sigma)+0.25 μM KAAD cyclopamine (EMD Millipore)+100 ng/mL recombinant human Noggin (R&D systems) for 4 days, then high-glucose DMEM+1% B27+100 ng/mL Noggin+300 nM indolactam V (Stemgent)+1 μM ALK5 inhibitor II (Axxora) for 4 days.
Anterior foregut endoderm differentiation—cells at the definitive endoderm stage are treated with DMEM/F12+1×L-glu+1×B27+200 ng/mL Noggin+10 μM SB431542 (Stemgent) for 3 days. For hindgut endoderm differentiation, cells at the definitive endoderm stage were treated with A-RPMI+1×L-glu+1×P/S+2% FBS+500 ng/mL FGF4 (R&D systems)+5 μM CHIR for 4 days.
Hindgut endoderm differentiation—cells at the definitive endodermstage were treated with A-RPMI+13 L-glu+13 P/S+2% FBS+500 ng/ml FGF4 (R&D Systems)+5mMCHIR for 4 days.
Intermediate mesoderm differentiation—cells are treated with A-RPMI+1×L-glu+1×P/S+5 μM CHIR for 24, 36, or 48 hours, then A-RPMI+1×L-glu+1×P/S+100 ng/mL FGF2+1 μM retinoic acid for 2-3 days.
Cap mesenchyme differentiation—cells were treated with A-RPMI+13 L-glu+13 P/S+5 mM CHIR for 36 hours, then A-RPMI+13 L-glu+13 P/S+100 ng/ml FGF2+1 mM retinoic acid for 36-42 hours, then A-RPMI+13L-glu+13P/S+100 ng/ml FGF-9 (R&D Systems)+10 ng/ml activin A for 3 days.
For immunofluorescence studies, cultures are washed once with PBS (Invitrogen) and fixed in 4% paraformaldehyde for 15 min at room temperature (RT). Fixed cells are then washed three times in PBS and incubated in blocking buffer (0.3% Triton X-100 (Fisher Scientific) and 5% normal donkey serum (EMD Millipore) in PBS) for 1 hour at RT.
The cells are then incubated with primary antibody overnight at 4° C. or for 2 hours at RT in antibody dilution buffer (0.3% Triton X-100 and 1% BSA (Roche) in PBS). Cells are then washed three times in PBS and incubated with Alexa Fluor 488-, 555-, or 647-conjugated secondary antibodies (1:500) (Molecular Probes) in antibody dilution buffer for 1 hour at RT. For immunostaining with Biotinylated Lotus Tetragonolobus Lectin (LTL, Vector Labs), a Streptavidin/Biotin Blocking Kit (Vector Labs) and Alexa Fluor 488- or 647-conjugated Streptavidin (Molecular Probes) were used according to manufacturer's instructions.
Nuclei can be counterstained with DAPI (Sigma). A list of primary antibodies can be found in Table 1. Immunofluorescence is visualized using an inverted fluorescence microscope (Nikon Eclipse Ti, Tokyo, Japan). Quantification is performed by counting a minimum of five random fields at 10× magnification.
Total RNA is harvested and isolated from cells using the RNeasy Mini Kit (Qiagen). 1 μg RNA is used for reverse transcription with the M-MLV Reverse Transcriptase system (Promega), or 500 ng RNA is used for High Capacity cDNA Reverse Transcription Kits (Applied Biosystems). RT-PCR reactions can be run in duplicate using cDNA (diluted 1:10), 300 or 400 nM forward and reverse primers, and iQ SYBR Green Supermix (Biorad) or iTAQ SYBR Green Supermix (Biorad). Quantitative RT-PCR is performed using the iQ5 Multicolor Real-Time PCR Detection System (Biorad). Samples can be run with two technical replicates to ensure precision and accuracy. β-actin can be used as a housekeeping gene. Primer sequences are listed in Table 2.
Cells are dissociated using Accutase for 15 minutes, and cell clumps are removed with a 40 μm cell strainer (BD Biosciences). Cells are fixed with 2% PFA for 15 minutes on ice and then permeabilized with 0.1% Triton for 15 minutes on ice. Cells are blocked with PBS+5% donkey serum for 15 minutes on ice and incubated with primary antibodies (PAX2 1:1000, LHX1 1:100) for 30 minutes. After washing 3 times with 1% BSA in PBS, cells were incubated with secondary antibodies (Alexa Fluor 488-conjugated donkey antirabbit 1:5000, Cy5-conjugated donkey anti-mouse 1:2500 (Jackson ImmunoResearch)) for 20 minutes on ice. Cells are then washed three times with 1% BSA in PBS. Flow cytometry is performed using MACSQuant (Miltenyi Biotec), and data analysis is performed using FlowJo software. Optimal dilution ratios of antibodies is determined using a negative control human proximal tubular cell line (HKC-8) which does not express PAX2 or LHX1.
Immunochemistry protocol is based on previous methods for kidney explant cultures. Filters with cultured explants were rinsed once with PBS then fixed with 4% PFA in PBS for 30 minutes in a 24-well plate. Care was taken to submerge the explants to ensure even fixation. Following fixation, explants were washed three times in PBT (PBS with 0.1% Triton X-100) for 5 minutes each at room temperature with gentle rocking Explants were then incubated in blocking solution (PBT with 5% donkey serum) at room temperature with rocking Blocking solution was then removed and replaced with a primary antibody solution of diluted antibodies in PBT with 1% donkey serum and samples incubated overnight at 4° C. Antibody dilutions used: mouse anti-Human Nuclear Antigen (HNA), 1:250 (Millipore); rabbit anti-laminin 1:500 (Sigma). Explants were then washed with PBT three times for one hour each with rocking at room temperature. Secondary antibody solution (PBT+1% donkey serum) with 1:250 dilutions of Alexa Fluor 488-conjugated donkey anti-mouse and Alexa Fluor 568-conjugated donkey anti-rabbit antibodies (Invitrogen) were added and incubated for 1-2 hours at room temperature. Samples were then washed with PBT three times for 30 minutes each at room temperature, followed by a 10 minute incubation with DAPI, and three additional 5 minute washes with PBS. Explant samples where then mounted with Vectashield (Vector Labs) and examined using a Nikon C1 confocal microscope.
To develop a platform to target generation of IM, conditions most efficiently differentiate hPSCs into mesendoderm must first be identified (
An initial screen tested efficacy of WNT3A and activin A to induce expression of the primitive streak marker BRACHYURY (BRACHY). WNT3A alone, at a concentration of 500 ng/mL, induced BRACHY expression in 26.7±1.9% of cells after 24 hours of treatment (
Gene expression profiling of CHIR-induced cells revealed that expression of primitive streak genes (BRACHY, MIXL1, EOMES, FOXA2, and GSC) was rapidly upregulated within 24 hours of treatment, peaked between 36-48 hours, and decreased by 72 hours, a pattern consistent with the transient expression of these genes during gastrulation. In parallel, the induction of the mesendoderm state was accompanied by the loss of pluripotency as reflected by a reduction of OCT4 and NANOG mRNA (
To determine whether treatment with CHIR alone is sufficient to induce differentiation towards IM, the Inventors investigated the intrinsic multipotency of CHIR-induced mesendodermal cells by withdrawing CHIR from the culture media after either 24 or 48 hours of induction and allowing the cells to differentiate for another 3-4 days (
As proper differentiation of lateral plate mesoderm during embryonic development is dependent on higher BMP-4 signaling gradients, the Inventors investigated the expression of BMP-4 transcripts in CHIR-induced cells by quantitative RT-PCR. hPSCs treated with CHIR for 24 or 48 hours significantly upregulated BMP-4 on day 4 compared to DMSO-treated controls, demonstrating that induction with CHIR stimulated endogenous expression of BMP-4 (
To determine whether CHIR-induced cells can be diverted from the default lateral plate mesoderm fate, the Inventors applied high doses of activin A to hPSCs after 24 hours of CHIR treatment, resulting in successful generation of SOX17+FOXA2+ definitive endoderm with greater than 95% efficiency after 2-3 days of subsequent differentiation (
Having demonstrated that one can manipulate the fate of CHIR-treated cells with the time-sensitive addition of specific inducing factors, the Inventors screened candidate growth factors for the ability to induce the expression of the intermediate mesoderm (“IM”) marker PAX2. PAX2 is selected since it is an early marker of IM, and, unlike the markers OSR1 or LHX1 which are also expressed in the adjacent lateral plate mesoderm, PAX2 expression is restricted in mesoderm to the IM. Human PSCs were induced with CHIR for 24 hours, at which time CHIR was withdrawn and cells were treated with increasing doses of activin A, BMP-2, BMP-4, BMP-7, FGF2, or retinoic acid (“RA”). On day 4 of differentiation, modest increases in PAX2 expression, compared to a vehicle control, were seen in cells treated with low doses of BMP-2, BMP-7, and RA, and no PAX2 expression was seen in cells treated with either activin or BMP-4 (
It is observed, however, that approximately 50-60% of cells treated with FGF2 at a dose of 100 ng/mL are positive for PAX2 by immunostaining, suggesting that FGF2 can be a potential inducer of IM. The ability of FGF2 to induce PAX2 expression was dependent upon cells being pre-treated with CHIR, as the addition of FGF2 to hPSCs not initially induced with CHIR resulted in the absence of PAX2 expression on day 4 of differentiation (
Retinoic acid signaling has previously been demonstrated to play an important role in the early stages of kidney development. Because a small inductive effect on PAX2 expression with RA is observed, low dose RA were tested in combination with FGF2 to determine whether it could have a synergistic effect on PAX2 expression. While this does not result in a dramatic increase in PAX2 expression, the addition of 1 μM RA resulted in a marked increase in LHX1 expression, with the majority of cells co-expressing both PAX2 and LHX1 (
As PAX2 and LHX1 are both expressed in the developing IM, these cells are labeled as a putative IM cell population. The Inventors sought to optimize the efficiency of generating IM cells. After testing the effects of different durations of CHIR pre-treatment and assaying PAX2 expression from days 2 through 7 of differentiation, it was observed that induction of hPSCs with CHIR for 36 hours followed by FGF2 and RA resulted in PAX2 expression in greater than 70% of cells as early as day 3 of differentiation (
To determine the reproducibility of the described protocol in different hPSC lines, the Inventors tested the combination of CHIR induction for 36 hours followed by the addition of FGF2 and RA (ChFR) in three hESC lines and two hiPSC lines. Similar patterns of co-staining for PAX2 and LHX1 are observed in all cell lines with nearly identical efficiencies of differentiation (70-80%) in four of the five cell lines and a slightly reduced differentiation efficiency in one iPS cell line (
The Inventors then performed gene expression profiling of the putative IM cells using quantitative RTPCR. Consistent with the described protein expression data, the Inventors observed a marked upregulation of IM genes, including PAX2, LHX1, OSR1, and PAX8, on day 3 of differentiation, followed by a reduction in gene expression at day 5 (
To determine whether hPSC-derived PAX2+LHX1+IM cells have the capacity to give rise to more differentiated cell and tissue derivatives of IM, the Inventors withdrew FGF2 and RA from the culture media on day 3 of differentiation and cultured themin serum-free media, containing no additional growth factors or chemicals, for another week. Cell growth and proliferation continued under these conditions, and as early as day 7, tubular epithelial structures formed in parallel with the downregulation of PAX2 expression (
To further confirm the identity of these cells as embryonic kidney cells, the Inventors subjected the cells to kidney explant re-aggregation assays. Chimeric kidney explants can be created using well-known re-aggregation techniques. Briefly, embryonic kidneys at stage E12.5 (day of plug=E0.5) are isolated from timed pregnant females (Charles River). Complete urogenital systems are placed in DMEM (Corning Cellgro) and further dissected to isolate single E12.5 kidneys. 4-6 kidneys were incubated in TrypLE™ Express (Invitrogen) at 37° C. for 4 minutes. The enzyme is then quenched by adding Kidney Culture Media (KCM: DMEM+1×P/S+10% fetal bovine serum) and incubating at 37° C. for 10 minutes for recovery. Digested kidney rudiments were then transferred to a microcentrifuge tube with additional KCM and dissociated by repeated trituration. The cell suspension is then passed through a 100 μm pore size cell strainer before visualizing toconfirm single cell suspension and counting. Differentiated human pluripotent stem cells from day 3 and day 9 are dissociated with TrypLE, visualized, and counted. Re-aggregation is done by mixing 130,000 dissociated mouse kidney cells with 13,000 differentiated human cells in a microcentrifuge tube and centrifuging the chimeric mixture into a pellet at 700×g. The resulting chimeric pellet are then placed onto a Nucleopore Track-Etch Membrane filter disk (pore size=1 μm) (Whatman) 60, and the filter floated on 1 ml KCM+10 μM Y27632 61 in a 24-well tissue culture plate (two explants per 13 mm circular filter) and incubated for 24 hours. After the initial incubation, the media with Y27632 is replaced with KCM only and cultured for an additional 2 days.
IM cells are dissociated on days 3 (PAX2+LHX1+) or 9 (LTL+KSP+) of differentiation and recombined with dissociated cells from wild-type E12.5 mouse embryonic kidneys.
Human cells from day 3 can incorporate into mouse metanephric tissues, distributing in the interstitium; however, no tubular integration was observed. Human cells from day 9 are found not only in the mouse metanephric interstitium but are also identified within organized laminin-bounded structures which also contained mouse cells (
Following generation of intermediate mesoderm cells, the Inventors have further established a method to differentiate the intermediate mesoderm cells further into cells of the metanephric mesenchyme, which express the markers SIX2 and WT1. This population of expressing SIX2 and WT1 gives rise to most of the epithelial cells in the kidney, and further validates the identity of generated cells as primitive intermediate mesoderm cells.
As shown in
During embryonic kidney development, the CM comprises a population of multipotent nephron progenitor stem cells that express the transcription factor SIX2 and give rise to nearly all the epithelial cells of the nephron, with the exception of the collecting duct cells. Although SIX2 mRNA levels increased during stochastic differentiation into tubular structures (
In addition to forming chimeric laminin-bounded structures in recombination explant culture (
To confirm that this SIX2 expression was consistent with differentiation toward CM, the Inventors evaluated the expression of SALL1 and WT1, two other important markers of CM.34,45 Nearly all SIX2+ cells coexpressed SALL1 as seen by immunocytochemistry, and a subset of SIX2+ cells also coexpressed WT1 (
To test the competence of hPSC-derived SIX2+ cells to respond to canonical Wnt signaling, the Inventors treated cells on day 6 of differentiation with 5 mM CHIR for 24 hours, followed by withdrawal of CHIR. Within 24 hours of CHIR treatment, the Inventors observed distinct changes in cell morphology and the formation of tubular-like structures (
Described herein is a rapid, efficient, and highly reproducible system to induce intermediate mesoderm cells from hESCs and hiPSCs under precise, chemically defined, monolayer culture conditions. Robust generation of a BRACHYURY+MIXL1+ mesendodermal cell population with the use of CHIR99021 confirmed the potency of GSK-3β inhibitors to generate mesendoderm and established the proper platform for us to screen compounds which could effectively promote IM differentiation.
By investigating the differentiation kinetics of CHIR-treated hPSCs, the Inventors established that increasing exposure to CHIR resulted in differentiation towards a lateral plate mesoderm fate, but this default pathway could be altered by the precisely-timed addition of fate altering growth factors. This affirms the findings of prior reports demonstrating that mesodermal and endodermal cell fates are determined by a delicate time- and dose-dependent balance of Wnt, activin, BMP, and FGF signaling. These findings, however, contrast with those of a recent study by Tan and colleagues, in which the authors showed that prolonged exposure to GSK-3β inhibition, specifically with CHIR, promoted an endodermal rather than mesodermal fate. With the described differentiation conditions, definitive endoderm differentiation could only be achieved with the synergistic effect of CHIR and high-dose activin.
While the differentiation of hPSCs into cells of the cardiac, hepatic, pancreatic, and neuronal lineages have been widely reported, previous attempts to derive cells of the kidney lineage from hPSCs have been relatively few in number. An alternative to directed differentiation was recently demonstrated by means of direct reprogramming of immortalized human kidney cells into nephron progenitor-like cells; however, the efficiency of integration into kidney explant cultures was reportedly low. Others have reported induction of an intermediate mesoderm population using a stepwise combination of CHIR, activin, and BMP-7 signaling in engineered OSR1-GFP hiPSC cell lines, achieving efficiencies of greater than 90% of OSR1-GFP+ cells after 11-18 days of differentiation. However, because OSR1 is expressed in both the lateral plate and intermediate mesoderm during early mesoderm specification, this expression pattern does not distinguish intermediate from lateral plate mesoderm, and the proportion of OSR1+ cells which co-expressed other important IM markers such as PAX2 or WT1 was comparatively low.
The Inventors selected PAX2 and LHX1 as more specific markers of IM for the purpose of defining IM inducing culture conditions. It is important to note that the expression of PAX2 and LHX1 is not limited to the developing kidney during embryogenesis and can be seen at other stages of development in the eye, ear, and central nervous system; however, co-expression of PAX2 and LHX1 within the same domain has only been described in the developing kidney and dorsal spinal cord. Importantly, the above described result identify, for the first time, that FGF2 is a potent factor in inducing PAX2 expression in CHIR-induced mesendodermal cells. When combined with RA, this combination is able to robustly generate a PAX2+LHX1+IM cell population as confirmed by both immunocytochemistry and flow cytometry.
This described protocol is capable of achieving efficient IM differentiation within 3 days, which is considerably quicker than existing protocols while maintaining a high level of efficiency, and was highly reproducible in multiple hESC and hiPSC lines without the need for flow sorting. Interestingly, with the described culture conditions it was observed that the addition of BMP-7, which has been used as a component of other kidney-lineage differentiation protocols, did not have an synergistic effect in inducing IM differentiation. While the precise conditions for specifically generating other IM derivatives, including the adrenal cortices and gonads, have yet to be defined, the Inventors demonstrated that inducing PAX2+LHX1+ cells is sufficient for these cells to autonomously express WT1, a later marker of IM differentiation, and to form polarized, ciliated tubular structures which express markers of kidney proximal tubular cells and integrate into mouse metanephric cultures. These polarized tubular structures could reproducibly form in monolayer culture, in contrast to previous reports in which tubular structures derived from differentiated hPSCs cells could form only with 3D culture in vitro or after incorporation into mouse metanephric kidneys ex vivo.
Described herein is the first report of the generation of SIX2+ cells from hPSCs. The described method of using FGF9 to induce SIX2 expression is consistent with the important role of FGF9 in maintaining the nephron progenitor population during embryonic kidney development. As described, when SIX2+ cells were transplanted ex vivo into mouse metanephric cultures, they organized into structures that expressed LTL and laminin. In parallel, activation of canonical Wnt signaling in the SIX2+ cell population using CHIR resulted in the rapid formation of tubule-like structures in vitro in which cells downregulated SIX2 and expressed LTL. Although this result suggests that hPSC-derived SIX2+ cells can be induced to condense and epithelialize in a manner similar to that seen with CMin vivo, further studies are needed to determine the precise conditions for activating a program of kidney tubulogenesis.
In conclusion, it is demonstrated herein that sequential treatment with CHIR99021 and FGF2 and RA induces efficient differentiation of hPSCs into PAX2+LHX1+ intermediate mesoderm, and that these cells are capable of giving rise to polar ciliated tubular structures which express markers of kidney proximal tubular epithelial cells. The establishment of this system will facilitate and improve the directed differentiation of hPSCs into cells of the kidney lineage for the purposes of bioengineering kidney tissue and iPS cell disease modeling.
As described herein, the Inventors have established is a highly efficient system to differentiate hESCs and hiPSCs into cells of the intermediate mesoderm, these cells being capable of expressing IM-specific markers, PAX2+LHX1+, autonomous WT1 expression, in addition to formation of tubules expressing differentiated kidney markers such as LTL, cilia with polycystin-2 protein and integration into mouse embryonic kidney explant cultures Treatment of hPSCs with the GSK-3β inhibitor CHIR99021 induced BRACHYURY+MIXL1+ mesendoderm differentiate with nearly 100% efficiency. Whereas the absence of additional exogenous factors leads CHIR-induced mesendodermal cells to preferentially differentiate into lateral plate mesoderm with minimal IM differentiation, the sequential treatment of hPSCs with CHIR followed by FGF2 and retinoic acid generated PAX2+LHX1+ cells with remarkable speed, 3 days, and at high efficiency of up to 70-80%. The described protocols establish for the first time the effective role of FGF signaling in inducing IM differentiation in hPSCs and establish the most rapid and efficient system whereby hPSCs can be robustly differentiated into kidney tubulogenic PAX2+LHX1+IM cells. The addition of FGF-9 and activin more specifically differentiates PAX2+LHX1+ cells into cells expressing SIX2, SALL1, and WT1, markers of the nephron progenitor stemcell pool in the CM, further demonstrating that PAX2+LHX1+ cells have the potential to give rise to IM derivatives. The establishment of this system will facilitate and improve the directed differentiated of hPSCs into cells of the kidney lineage for the purposes of bioengineering kidney tissue and iPS cell disease modeling.
The various methods and techniques described above provide a number of ways to carry out the invention. Of course, it is to be understood that not necessarily all objectives or advantages described may be achieved in accordance with any particular embodiment described herein. Thus, for example, those skilled in the art will recognize that the methods can be performed in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objectives or advantages as may be taught or suggested herein. A variety of advantageous and disadvantageous alternatives are mentioned herein. It is to be understood that some preferred embodiments specifically include one, another, or several advantageous features, while others specifically exclude one, another, or several disadvantageous features, while still others specifically mitigate a present disadvantageous feature by inclusion of one, another, or several advantageous features.
Furthermore, the skilled artisan will recognize the applicability of various features from different embodiments. Similarly, the various elements, features and steps discussed above, as well as other known equivalents for each such element, feature or step, can be mixed and matched by one of ordinary skill in this art to perform methods in accordance with principles described herein. Among the various elements, features, and steps some will be specifically included and others specifically excluded in diverse embodiments.
Although the invention has been disclosed in the context of certain embodiments and examples, it will be understood by those skilled in the art that the embodiments of the invention extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses and modifications and equivalents thereof.
Many variations and alternative elements have been disclosed in embodiments of the present invention. Still further variations and alternate elements will be apparent to one of skill in the art. Among these variations, without limitation, are compositions for generating intermediate mesoderm, methods of generating intermediate mesoderm, cells and cell lines produced by the described methods and compositions, including undifferentiated cells and their differentiated progeny, and the particular use of the products created through the teachings of the invention. Various embodiments of the invention can specifically include or exclude any of these variations or elements.
In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
In some embodiments, the terms “a” and “an” and “the” and similar references used in the context of describing a particular embodiment of the invention (especially in the context of certain of the following claims) can be construed to cover both the singular and the plural. The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations on those preferred embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. It is contemplated that skilled artisans can employ such variations as appropriate, and the invention can be practiced otherwise than specifically described herein. Accordingly, many embodiments of this invention include all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
Furthermore, numerous references have been made to patents and printed publications throughout this specification. Each of the above cited references and printed publications are herein individually incorporated by reference in their entirety.
In closing, it is to be understood that the embodiments of the invention disclosed herein are illustrative of the principles of the present invention. Other modifications that can be employed can be within the scope of the invention. Thus, by way of example, but not of limitation, alternative configurations of the present invention can be utilized in accordance with the teachings herein. Accordingly, embodiments of the present invention are not limited to that precisely as shown and described.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2014/034031 | 4/14/2014 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61891546 | Oct 2013 | US |
