Injectable scaffold materials differ in their cell instructive effects on primary human myoblasts.

Scaffolds are materials used for delivery of cells for regeneration of tissues. They support three-dimensional organization and improve cell survival. For the repair of small skeletal muscles, injections of small volumes of cells are attractive, and injectable scaffolds for delivery of cells offer a minimally invasive technique. In this study, we examined in vitro the cell instructive effects of three types of injectable scaffolds, fibrin, alginate, and poly(lactic-co-glycolic acid)-based microparticles on primary human myoblasts. The myoblast morphology and progression in the myogenic program differed, depending on the type of scaffold material. In alginate gel, the cells obtained a round morphology, they ceased to proliferate, and entered quiescence. In the fibrin gels, differentiation was promoted, and myotubes were observed within a few days in culture, while poly(lactic-co-glycolic acid)-based microparticles supported prolonged proliferation. Myoblasts released from the alginate and fibrin gels were studied, and cells released from these scaffolds had retained the ability to proliferate and differentiate. Thus, the study shows that human myogenic cells combined with injectable scaffold materials are guided into different states depending on the choice of scaffold. This opens for in vivo experiments, including testing of the significance of the cell state on regeneration potential of primary human myoblasts.

Transplantation of islet-like cell clusters derived from human dental pulp stem cells restores normoglycemia in diabetic mice.

BACKGROUND AIMS: The success of islet transplantation for diabetes depends on the availability of an adequate number of allogeneic or autologous islets. Postnatal stem cells are now considered for the generation of physiologically competent, insulin-producing cells. Our group showed earlier that it is possible to generate functional islets from human dental pulp stem cells by using a serum-free cocktail in a three-step protocol. METHODS: We compared the yield of generated islet-like cell clusters (ICCs) from stem cells from pulps of human exfoliated deciduous teeth (SHED) and dental pulp stem cells from permanent teeth (DPSCs). ICCs derived from SHED were packed in immuno-isolatory biocompatible macro-capsules and transplanted into streptozotocin (STZ)-induced diabetic mice. Non-diabetic and diabetic controls were transplanted with macro-capsules with or without islets. RESULTS: SHED were superior to DPSCs. STZ diabetic mice alone and mice transplanted with empty macro-capsules exhibited hyperglycemia throughout the experiment, whereas mice transplanted with macro-capsules containing ICCs were restored to normoglycemia within 3-4 weeks, which persisted for >60 days. CONCLUSIONS: Our results demonstrate for the first time that ICCs derived from SHED reverse STZ diabetes in mice without immunosuppression and offer an autologous and non-controversial source of human tissue that could be used for stem cell therapy in diabetes.