Pluripotent Stem Cells Can Be Isolated from Human Peripheral Nerves after in vitro BMP-2 Stimulation

Abstract

We have recently identified a population of cells within the peripheral nerves of adult mice that can respond to BMP-2 exposure or physical injury to rapidly proliferate. More importantly, these cells exhibited embryonic differentiation potentials that could be induced into osteoblastic and endothelial cells in vitro. The current study examined human nerve specimens to compare and characterize the cells after BMP-2 stimulation. Fresh pieces of human nerve tissue were minced and treated with either BMP-2 (750ng/ml) or vehicle for 12 hours at 37{degrees}C, before digested in 0.2% collagenase and 0.05% trypsin-EDTA. Isolated cells were cultured in restrictive stem cell medium. Significantly more cells were obtained from the nerve pieces with BMP-2 treatment in comparison with the non-treated controls. Cell colonies were starting to form at day 3. Expressions of the 4 transcription factors Klf4, c-Myc, Sox2 and Oct4 were confirmed at both transcriptional and translational levels. The cells can be maintained in the stem cell culture medium for at least 6 weeks without changing morphologies. When the cells were switched to fibroblast growth medium, dispersed spindle-shaped cells were noted and became fibroblast activated protein- (FAP) positive following immunocytochemistry staining. The data suggested that human peripheral nerve tissue also contain a population of cells that can respond to BMP-2 and express all four transcription factors KLF4, Sox2, cMyc, and Oct4. These cells are capable to differentiate into FAP-positive fibroblasts. It is proposed that these cells are possibly at the core of a previously unknown natural mechanism for healing injury.