MATERIALS & METHODS: Isolation of the LGR+ ESC from the hair follicle follicular bulge involved digestion of harvested skin and subsequent sorting via fluorescence-activated cell sorting (FACS). Sorted LGR+ ESC were plated and expanded to P4 before being seeded; the scaffold used in all groups was a demineralized cortical bone scaffold (MTF KoreFiber®). 3 groups were established: 1 control group consisting of scaffold only in base media; 1 with human LGR+ ESC seeded on scaffold in base media; and 1 with human LGR+ ESC seeded on scaffold in osteoinduction media. Cellular adhesion/migration, proliferation, and apoptosis were assessed via the following tests to evaluate the biocompatibility of LGR+ ESC on scaffold: Alizarin Red Staining Assay; MTT Cell Growth Assay; and Toxilight apoptosis analysis. All tests were performed on Day 7, 14, and 21 except the Toxilight analysis, which was conducted on Days 11 and 19.
RESULTS: LGR+ ESC will differentiate into an osteogenic lineage and survive 7 days on a bone scaffold before apoptosis. Osteoinduction as measured by Alizarin Red Staining demonstrated peak osteoinduction on Day 7 with diminishing levels at timepoints thereafter. The Cytotoxicity Assay (Toxilight) demonstrated a significant apoptotic reduction in cells between Day 11 and 19.
CONCLUSIONS: Utilization of a novel stem cell population that is readily available from the patient's own skin for a previously unexplored indication (augmentation of osteogenesis) is important translational research. The findings of this study provide strong justification for continued development and future clinical trials of LGR+ ESC in augmenting in vivo osteogenesis. Ultimately, this understanding has the potential of offering new opportunities for development of innovative therapies to manage bone defects or complex fractures.
