{'fraction_non_alphanumeric': 0.022193211488250653, 'fraction_numerical': 0.0030461270670147957, 'mean_word_length': 4.955958549222798, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 1, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Biological characterization of cultured dermal papilla cells and hair follicle regeneration in vitro and in vivo.

BACKGROUND
Dermal papilla cells (DPC) are a group of mesenchyme-derived cells at the base of the hair follicle, where they regulate and control hair follicle growth through the expression and secretion of cytokines. Nevertheless, the role of DPC derived chemokines and other cytokines in the hair follicle biology remain speculative. In this study, we investigated the expression of basic fibroblast growth factor (bFGF), endothelin-1 (ET-1) and stem cell factor (SCF) in different passages of cultured DPC and their effects on the biological behaviour of DPC.


METHODS
The expression of bFGF, ET-1 and SCF in different passages of cultured DPC and their possible effects on the biological behavior of DPC are investigated using in situ hybridization and immunochemistry. In addition, we performed transplantation of hair follicle cells into nude mice. The cultured DPC, dermal sheath cells and fibroblast of human scalp, respectively, were mixed with cells of the hair follicle epithelium in different ratios, and then were cultured in hair follicle organotypic cultures or implanted into the subcutis of nude mice.


RESULTS
The expression of ET-1 and SCF in early passages of cultured DPC became stronger, but turned weaker and even negative in late passages (> 6 passages). Hair follicle-like structures were formed after DPC combined with the cells of hair follicle epithelium cells in hair follicle organotypic cultures. When hair follicle organotypic cultures were implanted into the subcutis of nude mice, the relative intact hair follicles were formed. After the transplantation of hair follicle cells into the nude mice, the hair follicle-like structure was formed in the group that contained DPC mixed with hair follicle epithelium cells. However, no hair follicles were formed in the other two groups. It was found that the higher the expression of ET-1 and SCF in DPC, the stronger the ability of DPC to induce hair follicle regeneration.


CONCLUSIONS
The cultured DPC can induce hair follicle regeneration and sustain hair growth in vivo and in vitro. Moreover, the expression of ET-1 and SCF is correlated with the ability of DPC inducing hair follicle regeneration.