Patent Application
20140212875
The invention relates generally to the field of cell culture and more specifically to the field of determining cell type.
Brown adipose tissue (BAT) plays a key role in the evolutionarily conserved mechanisms underlying energy homeostasis in mammals. It is characterized by fat vacuoles 5-10 microns in diameter and expression of uncoupling protein 1 (UCP1), central to the regulation of thermogenesis. In the human newborn, depots of BAT are typically grouped around the vasculature and solid organs. These depots maintain body temperature during cold exposure by warming the blood before its distribution to the periphery. They also ensure an optimal temperature for biochemical reactions within solid organs. BAT had been thought to involute throughout childhood and adolescence. Recent studies, however, have confirmed the presence of active brown adipose tissue in adult humans with depots residing in cervical, supraclavicular, mediastinal, paravertebral and suprarenal regions. While human pluripotent stem cells have been differentiated into functional brown adipocytes in vitro and inducible brown adipocyte progenitor cells have been identified in murine skeletal muscle and white adipose tissue, metabolically active brown adipose tissue derived stem cells have not been identified in adult humans to date.
The present invention addresses this issue.
In one aspect the invention relates to a method of distinguishing a brown adipose cell from a white adipose cell. In one embodiment the method includes measuring the expression level of one or more genes in an adipose cell; comparing the measured expression levels to a control, and correlating the expression level of the one or more genes to an identity as a white adipose cell or a brown adipose cell. In one embodiment the one or more genes are selected from the genes listed in
In one embodiment the method measures the levels of at least two, at least three, at least four, at least five, at least 6, at least 7, at least 8, at least 9, at least 10, or at least 11 genes. In another embodiment the method measures the levels of any one of ELOVL3, INHBB, PPARGC1A, or UCP1. In yet another embodiment the method measures the levels of any two of ELOVL3, INHBB, PPARGC1A, or UCP1. In still yet another embodiment the method measures the levels of any three of ELOVL3, INHBB, PPARGC1A, or UCP1. In one embodiment the method measures the levels of ELOVL3, INHBB, PPARGC1A, and UCP1.
In another aspect the invention relates to a method of differentiating an adipose stem cell. In one embodiment the method includes inducing differentiation of an adipose stem cell in vitro; and distinguishing the differentiated stem cell. In another embodiment the inducing is performed by contacting the adipose stem cell with a brown adipose cell differentiation media. In yet another embodiment the inducing is performed by contacting the adipose stem cell with FNDC5.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. The present teachings described herein will be more fully understood from the following description of various illustrative embodiments, when read together with the accompanying drawings. It should be understood that the drawings described below are for illustration purposes only and are not intended to limit the scope of the present teachings in anyway.
Briefly, for this study, human adipose tissues were biopsied and analyzed with immunohistochemistry and primary cell isolation. Primary cells isolated from adipose explants were expanded and their growth kinetics, karyotyping, flow cytometry and immunocytochemistry were determined. Passage-2 cells were directionally differentiated into osteogenic, chondrogenic, white adipogenic and brown adipogenic lineages on plastic and also differentiated into brown adipocytes on porous extracellular matrix scaffolds. Differentiation was confirmed by Western blot, immunohistochemistry, cytochemistry, scanning electron microscopy (SEM), and quantitative real-time PCR. Functional brown fat differentiation was confirmed by fatty acid uptake and mitochondrial respiration, as measured by the oxygen consumption rate (OCR).
Mediastinal adipose tissues were obtained from 54 patients undergoing cardiac surgery. The group included 44 males and 10 females and had a mean ±SE age 72.4±12 yr. (range 28-84 yr.).
The excised tissue was cut into 3 mm pieces and explanted onto a 6 well dish and grown in DMEM low glucose, 10% XcytePL™ Supplement (JadiCell, Phoenix, Ariz.), 1X Glutamax, and 1X MEM-NEAA (Life Technologies, Carlsbad, Calif.) and cultured in 5% CO2/37° C.
RNA was isolated and DNaseI treated using the RNAqueous-4PCR Kit (Life Technologies AM1914 (Life Technologies, Carlsbad, Calif.)) per manufacturer's protocol.
First strand cDNA was synthesized using the RI' First Strand Kit (SABiosciences 330401) (SABiosciences, Valencia, Calif.) per manufacturer's protocol.
PCR was carried out on RT2 Profiler PCR Arrays using RT2SYBR Green qPCR Mastermix (SABiosciences 330521) in an Eppendorf Mastercycler ep realplex 4 pcr machine (Eppendorf, Hauppauge, N.Y.) per manufacturer's protocol.
The following RT2 Profiler PCR Arrays and individual gene primers were used:
Delta delta (ΔA) Ct based fold-change calculations were performed using the RT2 Profiler PCR Array Data Analysis Web Portal version 3.5 provided by SABiosciences at: http://pcrdataanalysis.sabiosciences.com/pcr/arrayanalysis.php
Total RNA was purified and DNase-treated from individual wells of 24-well plates using the RNAqueous-Micro kit (Ambion AM1931(Life Technologies, Carlsbad, Calif.)) per manufacturer's protocol. 100 ng of each sample was reverse transcribed and pre-amplified using the RT2 PreAMP cDNA Synthesis Kit (SABiosciences 330241) (SABiosciences, Valencia, Calif.). The preamplified product was then amplified using the RT2 SYBR Green/ROX qPCR Master Mix (SABiosciences PA-012) (SABiosciences, Valencia, Calif.). Experiments were done in triplicate and data was analysed by the delta delta (ΔA) Ct method. The control gene used was HPRT1.
Cells were fixed with 4% paraformaldehyde. After blocking, cells were incubated with primary antibody diluted in 5% donkey serum. After washing cells were incubated with secondary antibody and counterstained with DAPI (Molecular Probes (Life Technologies, Carlsbad, Calif.)). For negative controls, incubation without primary antibody and with corresponding specific non-immune immunoglobulin (EMD Millipore, Billerica, Mass.) was used.
Directly conjugated antibodies used: HLA-DP DQ DR (BD Biosciences,), CD90, LIN, CD166, STRO-1, SSEA-4, CD44, CD106, CD73, CD117, CD105, HLA-ABC, CD86, CD63, CD9, CD80 (Biolegend, San Diego, Calif.), CD45, CD133, and CD34 (Miltenyi Biotech, Bergisch Gladbach, Germany). After staining, the cells were fixed and analyzed using a FACSCanto II analyzer (BD Biosciences, Franklin Lakes, N.J.).
Cells were plated in 6-well dishes at a density of 50,000 cells/well. White or brown adipogenesis differentiation medium was added. For brown adipogenesis, FNDC5 was added 6 days post induction. Fatty acid binding protein 4 (FABP4) immunocytochemistry and 0.3% Oil Red O (Sigma Aldrich, St. Louis, Mo.) was used for staining to detect intracellular lipid accumulation (Data not shown).
Cells were plated in 6 well dishes at a density of 50,000 cells/well. StemPro® Osteogenesis Differentiation medium ((Life Technologies, Carlsbad, Calif.)) was added. 2% Alizarian Red S (Sigma Aldrich, St. Louis, Mo.) was used for staining to detect de novo formation of bone matrix.
500,000 cells/15 ml tube were pelleted and induced with StemPro® Chondrogenesis Differentiation medium ((Life Technologies, Carlsbad, Calif.)). 1% Alcian Blue (Sigma Aldrich, St. Louis, Mo.) was used to detect sulfated glycosaminoglycans.
Analysis began with the replacement of growth media with HBSS Buffer with 20 mM HEPES and 0.2% fatty free BSA. Cells were placed in the incubator for 1.5 h, QBT Fatty Acid Uptake (Molecular Devices, Sunnyvale, Calif.) media was added to the wells and fluorescence was analyzed every minute in a Bio-Tek Synergy HT (Bio Tek, Winooski, Vt.).
The oxygen consumption rate (OCR) was performed using a Seahorse Bioscience XF-24 instrument (Seahorse Bioscience, Billerica, Mass.). Analysis was performed by replacing the growth media with XF assay media and incubating in a CO2 free chamber for 1 h. The XF Cell Mito Stress Test simultaneously analyzed basal respiration, ATP turnover, proton leak, spare respiratory capacity and glycolysis.
Samples were fixed and embedded for routine TEM. They were then examined on an FEI Tecnai T-12 (FEI Hillsboro, Oreg.) at 120 KV.
Scaffolds were fixed and post fixed in 2% osmium tetroxide, dehydrated through a series of ethanol washes, dried with hexamethyldisilazane. Scaffolds were then sputter coated with gold and imaged with a scanning electron microscope under high vacuum.
In
Table 1 is a list of genes expressed by brown and white MSC as measured against a standard along with a measure of their expression relative to the standard. Thus for example The expression of the gene ANXA5 is 1.178 fold higher in brown than in the standard.
These results uniquely demonstrate a resident stem cell population within depots of brown adipose tissue from adult human mediastinum. Cells from this tissue exhibit multi-lineage potential with capacities to undergo osteogenesis, chondrogenesis and both brown and white adipogenesis. Directionally differentiated brown adipocytes exhibit a distinct morphology and gene expression profile, with functional properties characteristic of brown adipose tissue in vivo. These brown adipose-derived stem cells may offer a new target to activate and restore energy homeostasis in vivo for the treatment of obesity and related metabolic disorders.
It is to be understood that while the disclosure has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims.
This application claims priority to U.S. Provisional applications 61/756,857 filed Jan. 25, 2013 and 61/757,900 filed Jan. 29, 2013; the contents of each are herein incorporated in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61756857 | Jan 2013 | US | |
| 61757900 | Jan 2013 | US |
