| The overall goal of the study was to develop a delivery system for a potential bone tissue engineering application focusing on fabrication of gelatin microbubble (MB) based PLGA scaffolds capable of recruiting Mesenchymal stem cells (MSCs) and delivering bioactive molecules. Challenges associated with inefficient use of stem cells, scaffolding techniques and poor understanding of the role of growth factors hinders the success of tissue engineering strategies.;A major challenge with the use of autologous stem cells is its low proliferation and migratory capacity. Our lab previously established that using a biomaterial implant, autologous MSCs can be directed and recruited in large numbers at the implantation site using signaling molecules. Preserving bioactivity of these molecules was one major concern. To eliminate this problem, our lab fabricated albumin MB based scaffolds that were able to preserve the bioactivity and deliver growth factors.;As albumin was associated with poor cell attachment and infiltration, we made use of gelatin MB in this study as it is known for its cell adhesion properties. Gelatin MB concentration in polymer solutions was optimized based on numerous studies that assessed the physical, mechanical, and cell interaction properties. Out of 5% w/v gelatin, 10% w/v gelatin, and 20% w/v gelatin used, 10% w/v gelatin scaffold fared better in terms of load bearing capacity, dispersion of gelatin in scaffold matrix, and its pore size. Various growth factors like SDF1-&agr;, BMP-2, and Epo were tested for potentiating MSC migration and differentiation in vitro. Among them, Epo came out to be a highly potent recruiter of MSCs and an osteoinductive agent in vitro. They were then loaded into gelatin MB PLGA scaffolds and the ability of such scaffolds to deliver growth factors over time was evaluated. Scaffold with these growth factors alone or in combination was also evaluate in vivo for bone regenerative applications in vivo in an animal model for bone regeneration. Our results show that Epo was a highly potent recruiter of MSCs and an osteoinductive factor. In fact the effect of Epo alone was more pronounced than BMP-2 and surprisingly Epo+BMP-2. |
