The Antimicrobial Peptide Human Beta-Defensin-3 Is Induced by Platelet-Released Growth Factors in Primary Keratinocytes.

Platelet-released growth factors (PRGF) and its related clinically used formulations (e.g., Vivostat Platelet-Rich Fibrin (PRF®)) contain a variety of chemokines, cytokines, and growth factors and are therefore used to support healing of chronic, hard-to-heal, or infected wounds. Human beta-defensin-3 (hBD-3) is an antimicrobial peptide inducibly expressed in human keratinocytes especially upon wounding. The potent antimicrobial activity of hBD-3 together with its wound closure-promoting activities suggests that hBD-3 may play a crucial role in wound healing. Therefore, we analyzed the influence of PRGF on hBD-3 expression in human primary keratinocytes in vitro. In addition, we investigated the influence of Vivostat PRF on hBD-3 expression in artificially generated human skin wounds in vivo. PRGF treatment of primary keratinocytes induced a significant, concentration- and time-dependent increase in hBD-3 gene expression which was partially mediated by the epidermal growth factor receptor (EGFR). In line with these cell culture data, in vivo experiments revealed an enhanced hBD-3 expression in experimentally produced human wounds after the treatment with Vivostat PRF. Thus, the induction of hBD-3 may contribute to the beneficial effects of thrombocyte concentrate lysates in the treatment of chronic or infected wounds.

Platelet-Released Growth Factors Induce Differentiation of Primary Keratinocytes.

Autologous thrombocyte concentrate lysates, for example, platelet-released growth factors, (PRGFs) or their clinically related formulations (e.g., Vivostat PRF®) came recently into the physicians' focus as they revealed promising effects in regenerative and reparative medicine such as the support of healing of chronic wounds. To elucidate the underlying mechanisms, we analyzed the influence of PRGF and Vivostat PRF on human keratinocyte differentiation in vitro and on epidermal differentiation status of skin wounds in vivo. Therefore, we investigated the expression of early (keratin 1 and keratin 10) and late (transglutaminase-1 and involucrin) differentiation markers. PRGF treatment of primary human keratinocytes decreased keratin 1 and keratin 10 gene expression but induced involucrin and transglutaminase-1 gene expression in an epidermal growth factor receptor- (EGFR-) dependent manner. In concordance with these results, microscopic analyses revealed that PRGF-treated human keratinocytes displayed morphological features typical of keratinocytes undergoing terminal differentiation. In vivo treatment of artificial human wounds with Vivostat PRF revealed a significant induction of involucrin and transglutaminase-1 gene expression. Together, our results indicate that PRGF and Vivostat PRF induce terminal differentiation of primary human keratinocytes. This potential mechanism may contribute to the observed beneficial effects in the treatment of hard-to-heal wounds with autologous thrombocyte concentrate lysates in vivo.

Platelet-released growth factors induce psoriasin in keratinocytes: Implications for the cutaneous barrier.

Millions of patients around the world suffer minor or major extremity amputation due to progressive wound healing complications of chronic or infected wounds, the therapy of which remains a challenge. One emerging therapeutic option for the treatment of these complicated wounds is the local application of an autologous thrombocytes concentrate lysate (e.g. platelet-released growth factors ((PRGF)) or Vivostat PRF®) that contains a multitude of chemokines, cytokines and growth factors and is therefore supposed to stimulate the complex wound healing process. Although PRGF and Vivostat PRF® are already used successfully to support healing of chronic, hard-to-heal and infected wounds the underlying molecular mechanisms are not well understood. Psoriasin, also termed S100A7, is a multifunctional antimicrobial protein expressed in keratinocytes and is involved in various processes such as wound-healing, angiogenesis, innate immunity and immune-modulation. In this study, we investigated the influence of PRGF on psoriasin expression in human primary keratinocytes in vitro and the influence of Vivostat PRF® on psoriasin expression in experimentally generated skin wounds in vivo. PRGF treatment of primary keratinocytes caused a significant concentration- and time-dependent increase of psoriasin gene and protein expression in vitro that were partially mediated by the epidermal growth factor receptor (EGFR) and the interleukin-6 receptor (IL-6R). In accordance with these cell culture data, Vivostat PRF® induced a significant psoriasin gene and protein expression when applied to artificially generated skin wounds in vivo. The observed psoriasin induction in keratinocytes may contribute to the wound healing-promoting effects of therapeutically used thrombocyte concentrate lysates.

Platelet-released growth factors induce the antimicrobial peptide human beta-defensin-2 in primary keratinocytes.

Platelet-released growth factors (PRGF) and its related clinically used formulations [e.g. Vivostat platelet-rich fibrin (PRF(®) )] are thrombocyte concentrate lysates that support healing of chronic, hard-to-heal and infected wounds. Human beta-defensin-2 (hBD-2) is an antimicrobial peptide expressed in human keratinocytes exhibiting potent antimicrobial activity against wound-related bacteria. In this study, we analysed the influence of PRGF on hBD-2 expression in human primary keratinocytes and the influence of Vivostat PRF(®) on hBD-2 expression in experimentally generated skin wounds in vivo. Treatment of primary keratinocytes with PRGF caused a significant increase in hBD-2 gene and protein expressions in a concentration- and time-dependent manner. The use of blocking antibodies revealed that the PRGF-mediated hBD-2 induction was partially mediated by the epidermal growth factor receptor and the interleukin-6 receptor (IL-6R). Luciferase gene reporter assays indicated that the hBD-2 induction through PRGF required activation of the transcription factor activator protein 1 (AP-1), but not of NF-kappaB. In concordance with these cell culture data, Vivostat PRF(®) induced hBD-2 expression when applied to experimentally generated skin wounds. Together, our results indicate that the induction of hBD-2 by thrombocyte concentrate lysates can contribute to the observed beneficial effects in the treatment of chronic and infected wounds.