Co-delivery of the embedded growth factor-loaded microspheres and adult stem cells in a hydrogel matrix was studied for its potential as a cell-based therapeutic strategy for cartilage regeneration in partial thickness chondral defects. A photopolymerizable N-methacrylate glycol chitosan (MGC) was employed to form an in situ gel that was embedded with two formulations of growth factor-loaded microspheres and human adipose-derived stem cells (ASC). The polymeric microspheres were used as a delivery vehicle for the controlled release of growth factors to stimulate differentiation of the ASC towards the chondrocyte lineage. The microspheres were made of amphiphilic low molecular weight (Mn < 10,000 Da) poly(1,3-trimethylene carbonate-co--caprolactone)-b-poly(ethylene glycol)-b-poly(1,3-trimethylene carbonate-co--caprolactone) (P(TMC-CL)2-PEG)). This triblock copolymer is solid below 100C, but liquid with a low degree of crystallinity at physiological temperature and degrades slowly, and so acidic degradation products do not accumulate locally. Bone morphogenetic protein-6 (BMP-6) and transforming growth factor-3 (TGF-3) were delivered at 5 ng/day with initial bursts of 14.3 and 23.6%, respectively. Both growth factors were highly bioactive when released, retaining greater than 95% bioactivity for 33 days as measured by cell-based assays. To improve ASC viability within the MGC vehicle, an RGD-containing ligand was grafted to the MGC backbone. Prior to chondrogenic induction within the MGC gel, ASC viability was assessed and greater than 90% of ASC were viable in the gel grafted with cell-adhesive RGD peptides as compared to that in non-RGD grafted gels. For ASC chondrogenesis induced by the sustained release of BMP-6 and TGF-3 in MGC gels, the ASC cellularity and glycosaminosglycan production were similar for 28 days. The ratio of collagen type II to I per cell (normalized to deoxyribonucleic acid content) in the microsphere delivery group was significantly higher than that of non-induced ASC or with soluble growth factor administration in the culture media, and increased with time. Thus, the co-delivery of growth factor-loaded microspheres and ASC in MGC gels successfully induced ASC chondrogenesis and is a promising strategy for cartilage repair. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2011-06-07 19:32:50.94
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/6546 |
| Date | 10 June 2011 |
| Creators | SUKARTO, Abby |
| Contributors | Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.)) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
| Relation | Canadian theses |
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