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Paul A.,McGill University | Cantor A.,McGill University | Shum-Tim D.,Divisions of Cardiac Surgery and Surgical Research | Prakash S.,McGill University
Molecular Biotechnology | Year: 2011

The ability of mesenchymal stem cells to self-renew and differentiate into specialized cell lineages makes them promising tools for regenerative medicine. Local injection and use of scaffolds had been employed earlier to deliver these cells; yet, an optimal delivery system remains to be identified. Here, using genipin, which is a non-toxic natural cross linker for proteins, we prepared alginate-chitosan polymeric microcapsules (GCAC) to develop an efficient stem cell delivery system. We investigated the properties of this membrane along with the encapsulated adipose tissue-derived stem cells (ASCs) and compared that with the widely used alginate poly-lysine (APA) membranes. The GCAC membrane was able to support cell viability, augment cell growth, and showed better results under external rotational and osmotic pressures with about 30% of the ruptured capsules in comparison to 60% ruptured APA capsules. The membrane also provided immune-protection to the entrapped cells as demonstrated by the lymphocyte proliferation assay. The capsule also has potential for long-term storage. The encapsulated four million ASCs also showed steady secretion of approximately 4600 pg vascular endothelial growth factor (VEGF) over 15-day time period comparable to that of free cells. Furthermore, the encapsulated ASCs showed around 3.8-fold increase in VEGF secretion after 72 h hypoxic conditions in comparison to normoxic conditions. This increased VEGF expression resulted in improved angiogenic potential of the bioactive capsules as noted by enhanced endothelial cell growth. GCAC encapsulation also did not show any effect on their differentiation ability. Thus, because of these biocompatible and bioactive attributes, genipin cross-linked polymeric microcapsules can emerge as a potentially important tool for improved stem cell-based therapy and cell delivery applications. © 2010 Springer Science+Business Media, LLC.


Prakash S.,McGill University | Paul A.,McGill University | Khan A.A.,McGill University | Shum-Tim D.,Divisions of Cardiac Surgery and Surgical Research
Journal of Biomedicine and Biotechnology | Year: 2010

The potential of genetically modified cardiomyoblasts in treating damaged myocardium is well known. However, efficient delivery of these cells is of major concern during treatment. The limiting factors are the massive cell death that occurs soon after their intramyocardial transplantation into the beating heart. To address these problems, we generated recombinant baculoviruses (BacMam viruses) which efficiently transduced cardiomyoblast cells under optimized conditions. These genetically modified cells were then protected in a new polymeric microcapsule using poly-ethylene-glycol (PEG), alginate, and poly-L-lysine (PLL) polymers for efficient delivery. Results showed that microcapsules maintain cell viability and support cell proliferation for at least 30 days. The capsules exhibit strong immunoprotective potential and have high mechanical and osmotic stability with more than 70% intact capsules. The encased transduced cells showed a rapid transgene expression inside the capsule for at least 15 days. However, preclinical studies are needed to further explore its long-term functional benefits. © 2010 Arghya Paul et al.


Paul A.,McGill University | Shum-Tim D.,Divisions of Cardiac Surgery and Surgical Research | Prakash S.,McGill University
Cardiovascular Engineering and Technology | Year: 2010

Bone marrow derived mesenchymal stem cell (BMSCs) therapy can significantly improve cardiac ventricular function following ischemic injury. Their potential can be further enhanced by using genetically modified cells, overexpressing certain therapeutic biomolecules. However, such therapy is limited by low efficiency of transplantation of the cells, secreting inadequate therapeutic proteins. To address these issues, we developed recombinant baculoviruses to genetically modify the BMSCs and investigated the potential of using polyethylene glycol (PEG) integrated alginate-chitosan microcapsules (AC) for efficient myocardial transplantation. The data indicates that the cells encapsulated in AC-PEG microcapsules grew rapidly from 80 cells per capsule to above 100 cells per capsule within a week, reaching a confluency of average 110 cells by day 9 of encapsulation. The microcapsules proved superior to commonly used AC microcapsules in terms of immune protection. After 11 days of co-culture of the encapsulated cells with highly confluent lymphocytes, the viable cell population in AC-PEG microcapsules was reduced by only 20%, whereas in AC microcapsules it was reduced to more than 50%. AC-PEG microcapsules also had significantly higher mechanical (65 vs. 10%) and osmotic (92 vs. 52%) stability than commonly used AC microcapsules as seen after 2 h of external stresses. The entrapped genetically modified cells showed highest transgene expression on day 1, which was gradually reduced to 48% after 1 week and to 14% after 2 weeks. This expression pattern was also dependant on initial viral incubation time, with 8 h incubation being the optimum. The encapsulated cells, transduced with baculovirus, also retained their inherent potential to differentiate into multiple lineages. Because of the above characteristics, the baculovirus transduced microencapsulated BMSCs have immense potential in myocardial cell-based gene therapy, although preclinical studies are needed to be done to establish their functional benefits on myocardial implantation. © 2010 Biomedical Engineering Society.


Paul A.,McGill University | Nayan M.,Divisions of Cardiac Surgery and Surgical Research | Khan A.A.,McGill University | Shum-Tim D.,Divisions of Cardiac Surgery and Surgical Research | Prakash S.,McGill University
International Journal of Nanomedicine | Year: 2012

The objective of this study was to develop angiopoietin-1 (Ang1)-expressing genetically modified human adipose tissue derived stem cells (hASCs) for myocardial therapy. For this, an efficient gene delivery system using recombinant baculovirus complexed with cell penetrating transactivating transcriptional activator TAT peptide/deoxyribonucleic acid nanoparticles (Bac-NP), through ionic interactions, was used. It was hypothesized that the hybrid Bac-NPAng1 system can efficiently transduce hASCs and induces favorable therapeutic effects when transplanted in vivo. To evaluate this hypothesis, a rat model with acute myocardial infarction and intramyocardially transplanted Ang1-expressing hASCs (hASC-Ang1), genetically modified by Bac-NPAng1, was used. Ang1 is a crucial pro-angiogenic factor for vascular maturation and neovasculogenesis. The released hAng1 from hASC-Ang1 demonstrated profound mitotic and anti-apoptotic activities on endothelial cells and cardiomyocytes. The transplanted hASC-Ang1 group showed higher cell retention compared to hASC and control groups. A significant increase in capillary density and reduction in infarct sizes were noted in the infarcted hearts with hASC-Ang1 treatment compared to infarcted hearts treated with hASC or the untreated group. Furthermore, the hASC-Ang1 group showed significantly higher cardiac performance in echocardiography (ejection fraction 46.28% ± 6.3%, P < 0.001 versus control, n = 8) than the hASC group (36.35% ± 5.7%, P < 0.01, n = 8), 28 days post-infarction. The study identified Bac-NP complex as an advanced gene delivery vehicle for stem cells and demonstrated its potential to treat ischemic heart disease with high therapeutic index for combined stem cell-gene therapy strategy. © 2012 Paul et al, publisher and licensee Dove Medical Press Ltd.


Paul A.,McGill University | Srivastava S.,Divisions of Cardiac Surgery and Surgical Research | Chen G.,Divisions of Cardiac Surgery and Surgical Research | Shum-Tim D.,Divisions of Cardiac Surgery and Surgical Research | Prakash S.,McGill University
Cell Biochemistry and Biophysics | Year: 2013

Recently, preclinical studies have shown that allogeneic adipose-derived stem cells (ASCs), like bone marrow-derived mesenchymal stem cell (BMSCs) have significant clinical benefits in treating cardiovascular diseases, such as ischemic/infarcted heart. In this study, we tested whether ASCs are also immune tolerant, such that they can be used as universal donor cells for myocardial regenerative therapy. The study also focuses on investigating the potential therapeutic effects of human ASCs (hASCs) for myocardial infarction in xenotransplant model, and compares its effects with that of hBMSCs. The in vitro study confirms the superior proliferation potential and viability of hASCs under normoxic and stressed hypoxic conditions compared with hBMSCs. hASCs also show higher potential in adopting cardiomyocyte phenotype. The major findings of the in vivo study are that (1) both hASCs and hBMSCs implanted into immunocompetent rat hearts with acute myocardial infarction survived the extreme environment of xenogeneic mismatch for 6 weeks; (2) both hASCs and hBMSCs showed significant improvement in myocardial pro/anti-inflammatory cytokine levels with no detectable inflammatory reaction, despite the lack of any immunosuppressive therapy; and (3) hASCs contributed to the remarkable improvement in cardiac function and reduced infarction which was significantly better than that of hBMSC and untreated control groups. Thus, our findings suggest the feasibility of using ASCs, instead of BMSCs, as universal donor cells for xenogeneic or allogeneic cell therapy. © 2011 Springer Science+Business Media, LLC.

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