Up-regulation of caveolin 1 mediated by chitosan activates Wnt/ β-catenin pathway in chronic refractory wound diabetic rat model

ABSTRACT

Diabetes mellitus (DM) can be implicated in the perturbations of vascular integrity and the dysfunction of angiogenesis. Chitosan has the advantage of promoting the vascular endothelial cell proliferation. However, the molecular mechanism of action in the promotion of wound healing by chitosan derivatives is still debated. In the current study, DM with chronic wound (CW) model rats were prepared and treated with chitosan. Vascular endothelial cells isolated from granulation tissues were conducted by RNA sequencing. Two thousand three hundred and sixteen genes were up-regulated, while 1,864 genes were down-regulated after chitosan treatment compared to CW group. Here, we observed that caveolin 1 (CAV1) was highly expressed induced by chitosan. Furthermore, we observed that CAV1 knockdown could compromise the activation of Wnt pathway by reduction of β-catenin in rat aortic endothelial cells (RAOECs) and brain endothelium four cells (RBE4s). Moreover, we determined a direct interaction between CAV1 and β-catenin by IP assay. The C-terminus of CAV1 and β-catenin (24 to 586 amino acids contributed to the interaction of these two proteins. Finally, the protein docking analysis indicated that the fragments of β-catenin (253–261 ‘FYAITTLHN’ and 292–303 ‘KFLAITTDCLQI’) might have affected the structure by CAV1 and facilitated the resistance to degradation. Taken together, our study demonstrates that chitosan can up-regulate CAV1 expression, and CAV1 can interact with β- catenin for promotion of canonical Wnt signaling pathway activity. Our results deepens the molecular mechanism of the Wnt pathway in vascular endothelial cells and is beneficial to developing new targets to assist in enhancing the pharmacological effect of chitosan on wound healing and angiogenesis against DM.

KEYWORDS

CAV1; β-catenin; chitosan;Wnt pathway; angiogenesis; diabetes mellitus.

Direct oral mucosal epithelial transplantation supplies stem cells and promotes corneal wound healing to treat refractory persistent corneal epithelial defects

ABSTRACT：Persistent corneal epithelial defects (PED) can lead to irreversible blindness, seriously affecting the social function and life quality of these patients. When it comes to refractory PED, such as limbal stem cell deficiency (LSCD), that does not respond to standard managements, stem cell therapy is an ideal method. Oral mucosal epithelium (OME) abundant with stem cells within the base, is a promising autologous biomaterial, with much resemblance to corneal epithelial structures. In this experiment, uncultured autologous rat OME was directly applied to alkali burned corneas. Clinical evaluations and histological analyses showed that the transplantation accelerated the healing process, presenting faster re-epithelization and better formation of corneal epithelial barrier. To further investigate the therapeutic mechanism, oral epithelium was transplanted to de-epithelialized cornea in vitro for organ culture. It could be observed that the oral epithelial cells could migrate to the corneal surface and form smooth and stratified epithelium. Immunofluorescence staining results showed that the reformed epithelium derived from OME, maintained stemness and transformed to corneal epithelial phenotype to some extent. Corneal stroma may provide the suitable microenvironment to promote the trans-differentiation of oral stem cells. Thus, both in vivo and in vitro experiments suggested that oral epithelium could play a positive role in treating refractory PED.

Keywords: Persistent corneal epithelial defects Oral mucosal epithelial transplantation Organ culture Stem cell microenvironment.

Does exercise improve healing of diabetic foot ulcers? A systematic review

Abstract

Background: For patients with diabetic foot ulcers, offloading is one crucial aspect of treatment and aims to redistribute pressure away from the ulcer site. In addition to offloading strategies, patients are often advised to reduce their activity levels. Consequently, patients may avoid exercise altogether. However, it has been suggested that exercise induces an increase in vasodilation and tissue blood flow, which may potentially facilitate ulcer healing. The aim of this systematic review was to determine whether exercise improves healing of diabetic foot ulcers.

Review: We conducted a systematic search of MEDLINE, CINAHL and EMBASE between July 6, 2009 and July 6, 2019 using the key terms and subject headings diabetes, diabetic foot, physical activity, exercise, resistance training and wound healing. Randomised controlled trials were included in this review.

Three randomised controlled trials (139 participants) were included in this systematic review. All studies incorporated a form of non-weight bearing exercise as the intervention over a 12-week period. One study conducted the intervention in a supervised setting, while two studies conducted the intervention in an unsupervised setting. Two studies found greater improvement in percentage wound size reduction in the intervention group compared with the control group, with one of these studies achieving statistically significant findings (p < 0.05). The results of the third study demonstrated statistically significant findings for total wound size reduction (p < 0.05), however results were analysed within each treatment group and not between groups.

Conclusion: This systematic review found there is insufficient evidence to conclusively support non-weight bearing exercise as an intervention to improve healing of diabetic foot ulcers. Regardless, the results demonstrate some degree of wound size reduction and there were no negative consequences of the intervention for the participants. Given the potential benefits of exercise on patient health and wellbeing, non-weight bearing exercise should be encouraged as part of the management plan for treatment of diabetic foot ulcers. Further research is required to better understand the relationship between exercise and healing of diabetic foot ulcers.

Keywords: Diabetic foot ulcer, Exercise, Physical therapy, Wound healing.

International comparison of pressure ulcer measures in long-term care facilities: Assessing the methodological robustness of 4 approaches to point prevalence measurement

Introduction: Pressure ulcer indicators are among the most frequently used performance measures in long-term care settings. However, measurement systems vary and there is limited knowledge about the international comparability of different measurement systems. The aim of this analysis was to identify possible avenues for international comparisons of data on pressure ulcer prevalence among residents of long-term care facilities. Material and methods: A descriptive analysis of the four point prevalence measurement systems programs used in 28 countries on three continents was performed. The criteria for the description and analysis were based on the scientific literature on criteria for indicator selection, on issues in international comparisons of data and on specific challenges of pressure ulcer measurements.

Results: The four measurement systems use a prevalence measure based on very similar numerator and denominator definitions. All four measurement systems also collect data on patient mobility. They differ in the pressure ulcer classifications used and the requirements for a head-to-toe resident examination. The regional or country representativeness of long-term care facilities also varies among the four measurement systems.

Conclusions: Methodological differences among the point prevalence measurement systems are an important barrier to reliable comparisons of pressure ulcer prevalence data. The alignment of the methodologies may be improved by implementing changes to the study protocols, such as aligning the classification of pressure ulcers and requirements for a head-to-toe resident skin assessment. The effort required for each change varies. All these elements need to be considered by any initiative to facilitate international comparison and learning.

The potential of a canister-based single-use negativepressure wound therapy system delivering a greater and continuous absolute pressure level to facilitate better surgical wound care

Abstract

       Two types of single-use negative-pressure wound therapy systems are currently available to treat surgical wounds: Canister-based and canisterless. This work was aimed to evaluate the performance of a canister-based vs a canisterless system, each with a different negative-pressure setting and technology for fluid management. Continuous delivery of a specified level of negative pressure to the wound bed is hypothesised to be important for promoting surgical wound healing, by achieving continuous reduction of lateral tension in the wound, particularly through decrease of skin stress concentrations around suture insertion sites. To test the above hypothesis, we developed a computational modelling framework, a laboratory bench-test for simulated clinical use and had further conducted a pre-clinical study in a porcine model for closed incision. We specifically focussed on the impact of effective fluid management for continuous delivery of a stable, consistent negative pressure and the consequences of potential losses of the pressure level over the therapy period. We found that a greater (absolute) negative-pressure level and its continuous, consistent delivery through controlled fluid management technology, by removing excess fluid from the dressing, provides far superior biomechanical performances. These conditions are more likely to result in better quality of the repaired tissues.

KEYWORDS

       animal study, bioengineering laboratory research, closed incision, finite element modelling, lateral tension sutures

Single cell transcriptomic landscape of diabetic foot ulcers

Diabetic foot ulceration (DFU) is a devastating complication of diabetes whose pathogenesis remains incompletely understood. Here, we profifile 174,962 single cells from the foot, forearm, and peripheral blood mononuclear cells using single-cell RNA sequencing. Our analysis shows enrichment of a unique population of fifibroblasts overexpressing MMP1, MMP3, MMP11, HIF1A, CHI3L1, and TNFAIP6 and increased M1 macrophage polarization in the DFU patients with healing wounds. Further, analysis of spatially separated samples from the same patient and spatial transcriptomics reveal preferential localization of these healing associated fifibroblasts toward the wound bed as compared to the wound edge or unwounded skin. Spatial transcriptomics also validates our fifindings of higher abundance of M1 macrophages in healers and M2 macrophages in non-healers. Our analysis provides deep insights into the wound healing microenvironment, identifying cell types that could be critical in promoting DFU healing, and may inform novel therapeutic approaches for DFU treatment.