Can fibroblast growth factors substitute for bovine pituitary extracts in culture systems for hair apparatus cells?

Development of xeno-free epithelial differentiation media for adherent, non-expanded adipose stromal vascular cell cultures

INTRODUCTION

Reconstruction of respiratory epithelium is critical for the fabrication of bioengineered airway implants. Epithelial differentiation is typically achieved using bovine pituitary extract (BPE). Due to the xenogenic nature and undefined composition of BPE, an alternative for human clinical applications, devoid of BPE, must be developed. The goal of this study was to develop two different BPE-free media, with and without select pituitary hormone (PH), which could initiate epithelial differentiation for use in human implantation.

METHODS

The ability of the two BPE-free media to initiate epithelial differentiation of adherent, non-expanded stromal-vascular cells grown on porcine small intestinal submucosa was compared to traditional BPE-containing media (M1). Nanostring^® was used to measure differences in gene expression of stemness (MSC), basal cell (basal), and ciliated markers (muco-cil), and staining was performed support the gene data.

RESULTS

Compared to baseline, both BPE-free media upregulated epithelial and stemness genes, however this was to a lower degree than BPE-containing media. In general, the expression of basal cell markers (COL17A1, DSG3, ITGA6, KRT6A, LOXL2) and secreted mucous proteins (PLUNC, MUC5B, SCGB2A1) was upregulated. The gene expression of ciliated markers C9orf24, TUBA3 and DNCL2B but not of the key transcription factor for cilagenesis FOXJ1 were upregulated, indicating that mucus-secreting cell differentiation occurs more rapidly than ciliogenesis. The ability of the adherent stromal vascular cells to upregulate gene expression of both epithelial and stemness markers suggests maintenance of the self-renewal capacity of undifferentiated and/or basal cell-like cells contributing to proliferation and ensuring a persisting source of cells for regenerative medicine applications.

CONCLUSION

This study provides the initial step to defining a BPE-free epithelial differentiation medium for clinical translation. Thus, either of the proposed BPE-free medium are viable alternatives to BPE-containing medium for partial epithelial differentiation for human translational applications.

Selective release of cytokines, chemokines, and growth factors by minced skin in vitro supports the effectiveness of autologous minced micrografts technique for chronic ulcer repair

A new effective surgical procedure to repair chronic ulcers called minced micrografts technique has been recently reported. The technique consists in spreading a finely minced skin sample upon the wound bed. In this study, we investigate the in vitro release of cytokines (interleukin-6, tumor necrosis factor-α, interleukin-1α, and granulocyte-colony stimulating factor), chemokines (monocyte chemoattractant protein-1 and growth-related oncogene-α), and growth factors (platelet-derived growth factor, basic fibroblast growth factor, vascular endothelial growth factor, hepatocyte growth factor, and nerve growth factor) by minced (referred to as the minced sample) vs. not minced (referred to as the whole sample) human skin biopsy samples from the same donor. Factor release in the culture medium at different time points was detected using a multiplexed protein assay. The minced sample, which could behave like the skin fragments used in vivo in the autologous minced micrografts technique, expressed higher levels of tumor necrosis factor-α, interleukin-1α, platelet-derived growth factor, and basic fibroblast growth factor, and lower levels of interleukin-6, monocyte chemoattractant protein-1, growth related oncogene-α, and vascular endothelial growth factor compared with the whole sample. In conclusion, mincing of healthy skin may allow appropriate regulation of the inflammatory phase of wound healing and could induce overexpression of some growth factors, which facilitates the proliferative phase of healing.

Vitamin D enhances mitogenesis mediated by keratinocyte growth factor receptor in keratinocytes

The hormonally active vitamin D metabolite, 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), and keratinocyte growth factor (KGF) belong to the network of autocrine and paracrine mediators in the skin. Both were shown to modulate keratinocyte proliferation, to reverse epidermal atrophy, to increase wound healing, and to reduce chemotherapy-induced alopecia. The overlap between their activities may suggest that vitamin D exerts some of its actions by modulation of KGF activities in the skin. This notion was examined by using HaCaT keratinocytes cultured in serum-free medium in the absence of exogenous growth factors and in the presence of the EGF receptor tyrosine kinase inhibitor AG 1478 that blocks their autonomous proliferation. These cells could be stimulated to proliferate by different fibroblast growth factors (FGFs). The relative mitogenic efficacy of basic FGF, acidic FGF, or KGF was in correlation with their affinities for the KGF receptor (KGFR). Forty-eight hour co-treatment with 1,25(OH)(2)D(3) enhanced KGFR-mediated cell proliferation in a dose dependent manner. Both ERK1/2 and c-Jun N-terminal kinase (JNK) were activated by the FGFs. Treatment with 1,25(OH)(2)D(3) increased the activation of ERK but reduced the activation of JNK. Treatment with 1,25(OH)(2)D(3) increased the levels of KGFR in the presence but not in the absence of KGF, probably due to inhibition of ligand-induced receptor degradation. Inhibition of protein kinase C with bisindolylmaleimide did not interfere with the effect of 1,25(OH)(2)D(3) on KGFR-mediated ERK activation. Our results support the notion that the paracrine KGF-KGFR system in the skin can act in concert with the autocrine vitamin D system in keratinocytes to promote keratinocyte proliferation and survival under situations of stress and injury.