The effect of VEGF-induced angiogenesis on the viability of microencapsulated cells in vivo.

摘要

The microencapsulation of cells in a semi-permeable polymer membrane has been investigated for decades as a platform for the cell-based delivery of therapeutic biomolecules. Previous work investigating the delivery of Vascular Endothelial Growth Factor (VEGF) from cells microencapsulated in HEMA-MMA copolymer demonstrated the ability VEGF-secreting capsules to increase local vascularization in a subcutaneous murine angiogenesis model. To determine whether this increased vascularization would enhance the survival of microencapsulated cells in vivo, a quantitative viability assay was developed using the detection of a secreted form of human placental alkaline phosphatase (SEAP) as a surrogate marker for encapsulated cell viability. The analysis of SEAP secretion from capsules implanted with and without VEGF-induced angiogenesis revealed that the increased local vascularization had no measurable effect on cell viability. In a follow-up study, micro-computed tomography was investigated as a means of evaluating the architecture and functional nature of vessels formed in response to VEGF delivery.