Risk factors for delayed healing in venous leg ulcers: a review of the literature

Patients with venous leg ulcers can be managed safely in the community ----results of an observational comparison study in Singapore

AIM

To examine the healing outcomes of patients with venous leg ulcers requiring compression bandaging in community care versus tertiary care.

METHOD

This was an analytical observational cohort study. Venous leg ulcer (VLU) patients who required compression bandaging were recruited from an outpatient vascular clinic between May 2021 and August 2022. Eligible patients received two-or four-layer compression bandaging and followed up with the community care or tertiary care centre nurses. The primary outcome was the difference in the total surface area of the VLU after 12 weeks, and the secondary outcome was the patient's quality of life, as measured by the Cardiff Wound Impact Schedule (CWIS).

RESULTS

Forty-seven VLU patients were recruited; 27 received compression bandaging in the community care and 20 by the tertiary care centre. Mean age 70 years old (SD 11.04). The two most prevalent comorbidities were hypertension (51.06 %) and diabetes mellitus (38.29 %). Among those who completed follow-up (12 weeks), the median difference of the total surface area of the VLU between community-based care (p = 0.02) versus tertiary-based care (0.003) was significant. However, there was no difference in the healing status between community and tertiary-based care (p = 0.68). There was no difference in the quality of life of patients between groups.

CONCLUSION

This first tropical study comparing VLU healing outcomes between community and tertiary care found no significant difference in healing with compression bandaging by nurses in either setting. However, the small sample size and high dropout rate limit the generalizability of the findings, necessitating a larger-scale study with longer follow-up. Despite these limitations, the study is a crucial step toward improving wound care services in Singapore, and highlights the need for further research to guide future community wound care implementation.

Skin-Derived ABCB5+ Mesenchymal Stem Cells for High-Medical-Need Inflammatory Diseases: From Discovery to Entering Clinical Routine

The ATP-binding cassette superfamily member ABCB5 identifies a subset of skin-resident mesenchymal stem cells (MSCs) that exhibit potent immunomodulatory and wound healing-promoting capacities along with superior homing ability. The ABCB5+ MSCs can be easily accessed from discarded skin samples, expanded, and delivered as a highly homogenous medicinal product with standardized potency. A range of preclinical studies has suggested therapeutic efficacy of ABCB5+ MSCs in a variety of currently uncurable skin and non-skin inflammatory diseases, which has been substantiated thus far by distinct clinical trials in chronic skin wounds or recessive dystrophic epidermolysis bullosa. Therefore, skin-derived ABCB5+ MSCs have the potential to provide a breakthrough at the forefront of MSC-based therapies striving to fulfill current unmet medical needs. The most recent milestones in this regard are the approval of a phase III pivotal trial of ABCB5+ MSCs for treatment of recessive dystrophic and junctional epidermolysis bullosa by the US Food and Drug Administration, and national market access of ABCB5+ MSCs (AMESANAR®) for therapy-refractory chronic venous ulcers under the national hospital exemption pathway in Germany.

Allogeneic ABCB5+ mesenchymal stem cells for treatment-refractory chronic venous ulcers: a phase I/IIa clinical trial

A significant number of chronic venous ulcers (CVUs) fail to heal despite of guideline-conform standard of care. Skin-derived ABCB5+ mesenchymal stem cells (MSCs) can dampen the sustained IL-1β-driven inflammation present in chronic wounds. Based on their wound healing-facilitating effects in a mouse CVU model and an autologous first-in-human study, ABCB5+ MSCs have emerged as a potential candidate for cell-based advanced therapy of non-healing CVUs. In the present interventional, multicenter, single-arm, phase I/IIa clinical trial, subjects whose CVU had emerged as standard therapy-resistant received one or two topical applications of 1×106 allogeneic ABCB5+ MSCs/cm2 wound area in addition to standard treatment. Out of 83 treatment-emergent adverse events, only three were judged related to the cell product; they were mild or moderate and recovered without sequelae. Wound size markedly decreased from baseline to week 12, resulting in a median wound size reduction of 76% (full analysis set, N=31), 78% (per-protocol set, N=27) and 87% (subset of responders; n=21). In conclusion, the study treatment was well tolerated and safe. The treatment elicited a profound wound size reduction within 12 weeks, identifying ABCB5+ MSCs as a potential candidate for adjunctive therapy of otherwise incurable CVUs. These results justify the conduct of a larger, randomized, controlled trial to confirm clinical efficacy.

Epidemiological investigation of vascular etiological examinations in the diagnosis and treatment of lower-extremity ulcers in China

The vascular causes of lower-extremity ulcers cannot be neglected because they can directly affect treatment methods. No detailed epidemiological statistics have described vascular etiological diagnosis in China. This study aimed to explore the prevalence of clinical vascular etiological examination of lower-extremity ulcers and improve the diagnosis and treatment effectiveness of lower-extremity ulcers. Data were collected from the WoundCareLog database, which includes 2413 cases of lower-extremity ulcers from 478 hospitals nationwide. Data analysis revealed that 1698 (70.4%) lower-extremity blood flow examinations (including physical examination [PE] and assistant examinations [AE]) were performed, of which 61.7% were PE, 10.4% were AE only, and 27.9% were the combined PE and AE[PAE]. The proportion of nonexaminations was higher in the nondiabetic group than in the diabetic group (χ² = 34.5; P < .01). The positive rates of vascular etiological examination in the diabetic and nondiabetic groups were 69.7% and 70.7%, respectively. Among the four economic regions of China, there were statistically significant differences in the use of the different examination methods. The examination of vascular diseases in lower-extremity ulcers in China has not been fully popularized and requires improvement; there was no statistically significant difference between examination rates by doctors and nurses, which is mainly based on PE. However, PE has certain rates of misdiagnosis and missed diagnosis. The false-positive and false-negative rates were 25.7% and 57.6%, respectively. The use of an AE can compensate for this deficiency by making diagnosis more precise, while the quantitative diagnostic criteria allow disease diagnosis to transcend geographical and operator differences and maximize uniformity. The vascular B-ultrasound examination is more suitable for the medical environment in China because of its mature technology, high hospital penetration rate, and low cost.

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 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.

Platelet Lysate-Modified Porous Silicon Microparticles for Enhanced Cell Proliferation in Wound Healing Applications

The new frontier in the treatment of chronic nonhealing wounds is the use of micro- and nanoparticles to deliver drugs or growth factors into the wound. Here, we used platelet lysate (PL), a hemoderivative of platelets, consisting of a multifactorial cocktail of growth factors, to modify porous silicon (PSi) microparticles and assessed both in vitro and ex vivo the properties of the developed microsystem. PL-modified PSi was assessed for its potential to induce proliferation of fibroblasts. The wound closure-promoting properties of the microsystem were then assessed in an in vitro wound healing assay. Finally, the PL-modified PSi microparticles were evaluated in an ex vivo experiment over human skin. It was shown that PL-modified PSi microparticles were cytocompatible and enhanced the cell proliferation in different experimental settings. In addition, this microsystem promoted the closure of the gap between the fibroblast cells in the wound healing assay, in periods of time comparable with the positive control, and induced a proliferation and regeneration process onto the human skin in an ex vivo experiment. Overall, our results show that PL-modified PSi microparticles are suitable microsystems for further development toward applications in the treatment of chronic nonhealing wounds.