A number of research groups in different areas of regenerative medicine are working on ways to wrap individual stem cells in supporting materials that enable the cells to both survive and behave as desired for long enough to produce results following transplantation. In this case, the focus is on hair regeneration:
The dermal papilla cell (DPC) is a type of highly specialized mesenchymal cells located in hair follicles (HF). Due to the primary role in the epithelial-mesenchymal interaction that enables hair-follicle morphogenesis and hair cycling, DPC has become an attractive cell source for hair regeneration to treat alopecia patients. However, DPCs tend to lose their function during in vitro culture. Hence, there exists a clear need to develop a microenvironment that can recapitulate the interactions within the native milieu of DPCs.
Layer-by-layer (LBL) nano-coating with biocompatible materials on the cell surface displays the versatility with tunable loading and release properties, which can provide a remodeled microenvironment for regulating cell function. Here, we developed a LBL self-assembly technique for single DPCs to create a nano-scale ultrathin extracellular matrix (ECM). We showed that the single cell-based LBL-encapsulation would not impact the viability, morphology, proliferation and intrinsic properties of DPCs. We then included fibroblast growth factor-2 (FGF-2) into the LBL nano-structure to regulate the DPC function. Finally, we performed in vivo hair reconstitution assays using LBL-encapsulated DPCs combined with freshly isolated epidermal cells (EPCs) and found this strategy can treat hair loss. Tests on nude mice showed that the implanted encapsulated cells caused abundant hair growth with the hair follicle organisation showing mature characteristics.