Patent Application
20060127384
The present invention regards the use of coenzyme Q10 (ubiquinone) as an antiapoptotic agent. More specifically, the invention provides the use of coenzyme Q10 for the prevention or inhibition of apoptosis in cutaneous and adipose cells and tissues. According to the invention, compositions containing coenzyme Q10 are conveniently used in plastic and reconstructive surgery, especially for lipofilling and flap graft.
Ubiquinone or coenzyme Q10 (2.3-dimethoxy-5-methyl-6-multiprenyl-1.4-benzoquinone) is a well-known component of the respiratory chain as well as an antioxidant molecule and free radical scavenger.
Previous studies demonstrated that the coenzyme Q10 is able to inhibit apoptosis in cultured keratocytes treated with the excimer laser irradiation, an apoptotic stimulus that determines free radical formation (3) and causes lowering of intracellular ATP levels. These effects have been also demonstrated in vivo (4).
More recently, it has also been shown that in response to any apoptotic stimulus ubiquinone directly inhibits disruption of the mitochondrial transmembrane electrochemical gradient as well as the opening of mitochondrial Permeability Transition Pore (mPTP) (5), whereby several molecules involved in caspase cascade activation, including Cytochrome C and APAF-1, are extruded to the cytoplasm thus provoking apoptosis.
EP1321138 discloses the use of coenzyme Q10 for the treatment of ocular pathologies involving apoptotic events caused by hypoxia, ischemia or lack of trophic factors.
WO01/37851 discloses the use of coenzyme Q10 for the local treatment of ophthalmologic pathologies following photoreactive therapy, refractive surgery and exposure to ultraviolet radiation.
The invention is based on the finding that coenzyme Q10 is able to prevent or inhibit apoptosis in adipocytes and cutaneous cells from explanted human tissues. Increased survival of explanted or cultured tissues and cells improves the feasibility and efficacy of human tissue transplantation.
Explanted tissues and cells are subjected to several treatments prior to their reintroduction in the human body. During these treatments, a high level of cell death is observed as a consequence of apoptotic events. Cells maintained in the presence of coenzyme Q10 are less susceptible to apoptosis. In particular, the number of apoptotic events result significantly reduced in adipocytes and cutaneous cells maintained in the presence of coenzyme Q10. This result was confirmed by measuring the amount of the apoptotic indicators caspases 3 and 9 in cells from explanted tissues, after subjecting the cells to several ex vivo treatments aimed at their subsequent implantation. The levels of caspases were reduced by more than 50% in the presence of coenzyme Q10. The decrease of caspase 9, which is an indicator of mitochondrial apoptosis, was accompanied by an equivalent decrease of caspase 3, which is involved in both the mitochondrial and transmembrane apoptotic pathways.
Without binding the invention to a specific mechanism of action, the effects observed with ubiquinone are likely due to an activity of apoptosis prevention exerted by the enzyme Q10 both as a free radical scavenger and through the regulation of the open/close state of the mitochondrial permeability transition pore.
Accordingly, in a first aspect the invention provides a method for preventing or inhibiting apoptosis in cells from explanted adipose or cutaneous human tissues, which comprises contacting ex vivo the tissues, or cells isolated therefrom, with coenzyme Q10.
In a preferred embodiment, coenzyme Q10, or a suitable composition thereof, is added to a culture of adipose or cutaneous tissues or cells; the addition can be effected at any stage of the treatment preceding cell or tissue implantation, in particular during fractionation, separation, centrifugation and freezing procedures. For these applications, coenzyme Q10 is preferably diluted in a water solution containing an amphipathic co-solvent such as polyethylene glycols and poloxamers, preferably Lutrol®.
Inhibition of apoptosis in adipocytes and cutaneous cells is important for plastic and reconstructive surgery, particularly for lipofilling and flap graft techniques. As used herein, flap graft refers to the transplantation of tissue portions that are either completely separated from donor blood vessels, and therefore have to be implanted in a highly vascularized recipient site, or that remain in contact with donor vessels (peduncle) and therefore can be implanted in a low-vascularized recipient site. In the technique known as lipofilling, the adipose tissue is collected with syringes, contacted with coenzyme Q10 and reinoculated in the body site to be treated.
The viability of transplanted tissues can be increased by apoptosis inhibition as a consequence of ischemia and reperfusion injury reduction, thereby allowing for the transplantation of larger tissue areas.
According to a further aspect, the invention provides the use of ubiquinone Q10 for the preparation of a pharmaceutical composition for preventing or inhibiting apoptosis in transplanted tissues, especially cutaneous and adipose tissues, to increase their survival, thriving and vascularization. In this case, coenzyme Q10 is preferably administered directly to the transplantion site. Suitable pharmaceutical formulations for topical administration include solutions, injectables, creams, ointments, gel, and controlled-release transdermic delivery systems. For use in therapy, coenzyme Q10 will be formulated with pharmaceutically acceptable carriers and excipients.
MATERIALS AND METHODS
Quantification of Apoptotic Factors (cytocrome c, caspase 3 and 9)
Adipocytes have been collected both manually using a “Luer-lock” 10 cc. syringe following Coleman's technique, and by a liposuctor with a negative pressure adjusted to maintain −680 mmHg. After the collection, half of the sample was treated with coenzyme Q10 dissolved in Lutrol (or another amphipathic molecule) at 10 μM concentration, as reported in previous works (1, 3). The other half of collected sample was treated with Lutrol (or another amphipathic molecule) alone. Both samples were then -centrifuged. The interphase and cell pellet were collected, following Coleman's technique (6) and maintained in liquid Nitrogen.
Preparation of protein cell lysates (6) is a modification of the -method described by Rioux (7).
Liposucted cell suspensions were centrifuged at 800 g for 10 minutes. 1 ml of lysis buffer (0.75 M NaCl, 10 mM HEPES, 1 mM EDTA, 1% Triton-X-100) containing a protease inhibitor mixture (final concentrations 1 μg/ml leupeptin, 10 μg/ml benzamidine, 1 μg/ml chymostatin, 1 μg/ml pepstatin A and 100 μg/ml PMSF) was added and the cell pellet was sonicated two times successively (20 sec, 100 W) to obtain whole cellular lysate. The lysate was further cleared by centrifugation at 10.000 g for 30 min in mini centrifuge. After removing the fat layer and the pellet of cellular debris, the protein content was quantified with Bradford reagent by spectrophotometry. Protein lysates (30 μg/lane) were separated by SDS-PAGE (10 and 15%) and analysed by Western blot analysis with specific antibodies.
Quantification of apoptotic factors was performed by densitometry.
Isolation of Adipocytes from Adipose Tissue
Modification of protocol described by Flower et al., Cytokine 21 (2003) 32-37.
For isolation, adipocyte tissue was quickly thawed, dissected with scissors into fine fragments in-digest solution consisting of Hank's buffer, supplemented with 2 mg/ml of collagenase (Type II, Sigma) and 1.5% BSA, and incubated at 37° C. for 1 hour in shaker-heater bath. The ratio of digest solution to adipose tissue was 4:1. The tissue digest was filtered through 200 μm Nylon mesh fabric in order to remove non digested tissue fragments. The adipocyte-containing layer and free oil were separated from the resulting stromovascular cell suspension by repeated centrifugation at 250×g for 5 minutes at 4° C. All the cells retrieved were morphologically typical mature adipocytes.
Detection of Apoptotic Adipocytes by Hoechst Staining
Isolated adipocytes in suspension were fixed with 4% paraformaldehyde for 20 min at RT (room temperature), washed 3 times with PBS and permeabilized for 5 min with 0.25% Triton X-100 in PBS solution. Washes with PBS were repeated 3 times for 5 min each time and the cells were stained with Hoechst 33258 (Sigma) nuclear dye for 30 min at 37° C. followed by washing in PBS 3 times for 5 min.
The stained cells (104) were affixed to polylysine-treated glass slides by gentle cyto-centrifugation or by spreading the cellular film directly on the surface, of the glass slide and mounted. Nuclear staining was examined under Nikon fluorescence microscope (20× and 40× magnification) equipped with camera. The results are expressed as the percentage of apoptotic cells (number of apoptotic cells/100 counted cells) in 10 random fields, performed by 3 independent observers.
Results
Cytochrome C is an enzyme involved in mobile electron transport and essential to energy conversion in all aerobic organisms (8). In mammalian cells, this highly conserved molecule is normally localized to the mitochondrial intermembrane space (9). Release of Cytochrome C into cytosol has been identified as an event necessary for execution of apoptosis (10). Western blot analysis of adipocyte protein lysates demonstrated that release of cytochrome C to cytoplasm (
The activities of both caspases 3 and 9 evaluated by Western blotting were higher when the adipocytes were collected with the liposuctor than following Coleman's technique. The addition of coenzyme Q10 prior to centrifugation and purification dramatically reduced the activities of both caspases in adipocytes collected with Coleman's technique (
Hoechst Staining method confirmed in skin graft the same results obtained with adipocytes. The percentage of apoptotic cells was dramatically lower in glass slides of Q10 treated cells than in glass slides of non treated cells (
