In situ-forming chitosan/nano-hydroxyapatite/collagen gel for the delivery of bone marrow mesenchymal stem cells

A biomimetic and thermosensitive gel scaffold was prepared from chitosan (CS), nano-hydroxyapatite (HA) and collagen (Col). The changes of storage modulus, loss modulus, pH and conductivity of the CS/HA/Col system as a function of temperature confirmed the liquid-to-gel phase transition process occurred under physiological conditions. The formed gel acted as a biocompatible substrate for the proliferation of rat bone marrow stem cells (rBMSCs) in vitro. rBMSCs suspension was co-injected with CS/HA/Col solution into Wistar rats. The injected rBMSCs survived in the CS/HA/Col gel for 28 days in vivo. The CS/HA/Col/rBMSCs gels induced less inflammatory reaction in the host tissue than the CS/HA/Col gels. Our results suggest that the CS/HA/Col system can be used to load rBMSCs in vitro homogeneously. The CS/HA/Col system can be injected into body in a minimally invasive manner and provides a biocompatible environment for rBMSCs survival in vivo.