Both human embryonic stem cells and induced pluripotent stem cells can self-renew indefinitely in culture; however, present methods to clonally grow them are inefficient and poorly defined for genetic manipulation and therapeutic purposes. Here we develop the first chemically defined, xeno-free, feeder-free synthetic substrates to support robust self-renewal of fully dissociated human embryonic stem and induced pluripotent stem cells. Material properties including wettability, surface topography, surface chemistry and indentation elastic modulus of all polymeric substrates were quantified using high-throughput methods to develop structure–function relationships between material properties and biological performance. These analyses show that optimal human embryonic stem cell substrates are generated from monomers with high acrylate content, have a moderate wettability and employ integrin α_vβ₃ and α_vβ₅ engagement with adsorbed vitronectin to promote colony formation. The structure–function methodology employed herein provides a general framework for the combinatorial development of synthetic substrates for stem cell culture.

Stem cells hold great potential as cell-based therapies to promote vascularization and tissue regeneration. However, the use of stem cells alone to promote angiogenesis remains limited because of insufficient expression of angiogenic factors and low cell viability after transplantation. Here, we have developed vascular endothelial growth factor (VEGF) high-expressing, transiently modified stem cells for the purposes of promoting angiogenesis. Nonviral, biodegradable polymeric nanoparticles were developed to deliver hVEGF gene to human mesenchymal stem cells (hMSCs) and human embryonic stem cell-derived cells (hESdCs). Treated stem cells demonstrated markedly enhanced hVEGF production, cell viability, and engraftment into target tissues. S.c. implantation of scaffolds seeded with VEGF-expressing stem cells (hMSCs and hESdCs) led to 2- to 4-fold-higher vessel densities 2 weeks after implantation, compared with control cells or cells transfected with VEGF by using Lipofectamine 2000, a leading commercial reagent. Four weeks after intramuscular injection into mouse ischemic hindlimbs, genetically modified hMSCs substantially enhanced angiogenesis and limb salvage while reducing muscle degeneration and tissue fibrosis. These results indicate that stem cells engineered with biodegradable polymer nanoparticles may be therapeutic tools for vascularizing tissue constructs and treating ischemic disease.