Effects of avotermin (transforming growth factor β3) in a clinically relevant pig model of long, full-thickness incisional wounds

Genome-wide transcriptional analysis of differentially expressed genes in diabetic, healing corneal epithelial cells: hyperglycemia-suppressed TGFβ3 expression contributes to the delay of epithelial wound healing in diabetic corneas

Patients with diabetes mellitus (DM) may develop corneal complications and delayed wound healing. The aims of this study are to characterize the molecular signatures and biological pathways leading to delayed epithelial wound healing and to delineate the involvement of TGFβ3 therein. Genome-wide cDNA microarray analysis revealed 1,888 differentially expressed genes in the healing epithelia of normal (NL) versus type 1 DM rat corneas. Gene ontology and enrichment analyses indicated TGFβ signaling as a major altered pathway. Among three TGFβ isoforms, TGF-β1 and β3 were upregulated in response to wounding in NL corneal epithelial cells (CECs), whereas the latter was greatly suppressed by hyperglycemia in rat type 1 and 2 and mouse type 1 DM models. Functional analysis indicated that TGF-β3 contributed to wound healing in NL corneas. Moreover, exogenously added TGF-β3 accelerated epithelial wound closure in type 2 rat and type 1 mouse DM corneas via Smad and PI3K-AKT signaling pathways, autoregulation, and/or upregulation of Serpine1, a well-known TGFβ target gene. Taken together, our study for the first time provides a comprehensive list of genes differentially expressed in the healing CECs of NL versus diabetic corneas and suggests the therapeutic potential of TGF-β3 for treating corneal and skin wounds in diabetic patients.

Strategies Demonstrating Efficacy in Reducing Wound Contraction In Vivo

SIGNIFICANCE

Scarring continues to present a significant clinical problem. Wound contraction leads to scarring and is mediated by myofibroblasts and contractile forces across the wound bed. Contracture formation can have a significant impact on the quality of life of the patient, particularly where function and appearance are affected.

RECENT ADVANCES

Novel tissue-engineered matrices, cell-based therapies, and medicinal therapeutics have shown significant reduction in wound contraction in in-vivo models, particularly at early time points. These have been accompanied in many cases by reduced numbers of myofibroblasts, and in some by increased angiogenesis and improved neodermal architecture.

CRITICAL ISSUES

There are no animal models that replicate all aspects of wound healing as seen in patients. Therefore, information obtained from in vivo studies should be assessed critically. Additional studies, in particular those that seek to elucidate the mechanisms by which novel therapies reduce contraction, are needed to gain sufficient confidence to move into clinical testing.

FUTURE DIRECTIONS

The use of knockout mouse models in particular has generated significant advances in knowledge of the mechanisms behind myofibroblast conversion and other factors involved in generating tension across the wound. Medicinal therapeutics and tissue-engineering approaches that seek to disrupt/alter these pathways hold much promise for future development and translation to clinical practice.

Targeting the TGFβ signalling pathway in disease

Many drugs that target transforming growth factor-β (TGFβ) signalling have been developed, some of which have reached Phase III clinical trials for a number of disease applications. Preclinical and clinical studies indicate the utility of these agents in fibrosis and oncology, particularly in augmentation of existing cancer therapies, such as radiation and chemotherapy, as well as in tumour vaccines. There are also reports of specialized applications, such as the reduction of vascular symptoms of Marfan syndrome. Here, we consider why the TGFβ signalling pathway is a drug target, the potential clinical applications of TGFβ inhibition, the issues arising with anti-TGFβ therapy and how these might be tackled using personalized approaches to dosing, monitoring of biomarkers as well as brief and/or localized drug-dosing regimens.