Porcine bladder extracellular matrix in paediatric pilonidal wound care: healing and patient experience evaluation

Evaluation of biocompatibility and angiogenic potential of extracellular matrix hydrogel biofunctionalized with the LL-37 peptide

BACKGROUND

Biomaterials must allow revascularization for a successful tissue regeneration process. Biomaterials formulated from the extracellular matrix (ECM) have gained popularity in tissue engineering because of their superior biocompatibility, and due to their rheological properties, ECM-hydrogels can be easily applied in damaged areas, allowing cell colonization and integration into the host tissue. Porcine urinary bladder ECM (pUBM) retains functional signaling and structural proteins, being an excellent option in regenerative medicine. Even some small molecules, such as the antimicrobial cathelicidin-derived LL-37 peptide have proven angiogenic properties.

OBJECTIVE

The objective of this study was to evaluate the biocompatibility and angiogenic potential of an ECM-hydrogel derived from the porcine urinary bladder (pUBMh) biofunctionalized with the LL-37 peptide (pUBMh/LL37).

METHODS

Macrophages, fibroblasts, and adipose tissue-derived mesenchymal stem cells (AD-MSC) were exposed pUBMh/LL37, and the effect on cell proliferation was evaluated by MTT assay, cytotoxicity by quantification of lactate dehydrogenase release and the Live/Dead Cell Imaging assays. Moreover, macrophage production of IL-6, IL-10, IL-12p70, MCP-1, INF-γ, and TNF-α cytokines was quantified using a bead-based cytometric array. pUBMh/LL37 was implanted directly by dorsal subcutaneous injection in Wistar rats for 24 h to evaluate biocompatibility, and pUBMh/LL37-loaded angioreactors were implanted for 21 days for evaluation of angiogenesis.

RESULTS

We found that pUBMh/LL37 did not affect cell proliferation and is cytocompatible to all tested cell lines but induces the production of TNF-α and MCP-1 in macrophages. In vivo, this ECM-hydrogel induces fibroblast-like cell recruitment within the material, without tissue damage or inflammation at 48 h. Interestingly, tissue remodeling with vasculature inside angioreactors was seen at 21 days.

CONCLUSIONS

Our results showed that pUBMh/LL37 is cytologically compatible, and induces angiogenesis in vivo, showing potential for tissue regeneration therapies.

An extracellular matrix hydrogel from porcine urinary bladder for tissue engineering: In vitro and in vivo analyses

BACKGROUND

The necessity to manufacture scaffolds with superior capabilities of biocompatibility and biodegradability has led to the production of extracellular matrix (ECM) scaffolds. Among their advantages, they allow better cell colonization, which enables its successful integration into the hosted tissue, surrounding the area to be repaired and their formulations facilitate placing it into irregular shapes. The ECM from porcine urinary bladder (pUBM) comprises proteins, proteoglycans and glycosaminoglycans which provide support and enable signals to the cells. These properties make it an excellent option to produce hydrogels that can be used in regenerative medicine.

OBJECTIVE

The goal of this study was to assess the biocompatibility of an ECM hydrogel derived from the porcine urinary bladder (pUBMh) in vitro using fibroblasts, macrophages, and adipose-derived mesenchymal stem cells (AD-MCSs), as well as biocompatibility in vivo using Wistar rats.

METHODS

Effects upon cells proliferation/viability was measured using MTT assay, cytotoxic effects were analyzed by quantifying lactate dehydrogenase release and the Live/Dead Cell Imaging assay. Macrophage activation was assessed by quantification of IL-6, IL-10, IL-12p70, MCP-1, and TNF-α using a microsphere-based cytometric bead array. For in vivo analysis, Wistar rats were inoculated into the dorsal sub-dermis with pUBMh. The specimens were sacrificed at 24 h after inoculation for histological study.

RESULTS

The pUBMh obtained showed good consistency and absence of cell debris. The biocompatibility tests in vitro revealed that the pUBMh promoted cell proliferation and it is not cytotoxic on the three tested cell lines and induces the production of pro-inflammatory cytokines on macrophages, mainly TNF-α and MCP-1. In vivo, pUBMh exhibited fibroblast-like cell recruitment, without tissue damage or inflammation.

CONCLUSION

The results show that pUBMh allows cell proliferation without cytotoxic effects and can be considered an excellent biomaterial for tissue engineering.

Traditional and advanced therapeutic modalities for wounds in the paediatric population: an evidence-based review

OBJECTIVE

Children can have non-healing wounds due to a wide range of pathologies, including epidermolysis bullosa (EB), pilonidal disease and Stevens-Johnson syndrome, with some causes being iatrogenic, including extravasation injuries and medical device-related hospital-acquired pressure ulcers. Furthermore, paediatric wounds are vastly different from adult wounds and therefore require a different treatment approach. While there are numerous types of dressings, topical remedies, and matrices with high-tier evidence to support their use in adults, evidence is scarce in the neonatal and paediatric age groups. The purpose of this review is to discuss the basic principles in paediatric wound management, as well as to present new treatment findings published in the literature to date. The benefits and risks of using different types of debridement are discussed in this review. Various topical formulations are also described, including the need to use antibiotics judiciously.

METHOD

Databases were searched for relevant sources including Pubmed, Embase, Web of Science and DynaMed. Search terms used included 'wound care', 'wound management', 'paediatrics', 'children', 'skin substitutes', and 'grafts'. Additionally, each treatment and disease entity was searched for relevant sources, including, for example: 'Apligraf', 'dermagraft', 'Manuka honey', 'antibiotic', 'timolol', and 'negative pressure wound therapy' (NPWT).

RESULTS

Amniotic membrane living skin equivalent is a cellular matrix that has been reportedly successful in treating paediatrics wounds and is currently under investigation in randomised clinical trials. Helicoll is an acellular matrix, which shows promise in children with recessive dystrophic EB. NPWT may be used as a tool to accelerate wound closure in children; however, caution must be taken due to limited evidence to support its safety and efficacy in the paediatric patient population. Integra has been reported as a useful adjunctive treatment to NPWT as both may act synergistically. Hospitalised children and neonates frequently have pressure ulcers, which is why prevention in this type of wound is paramount.

CONCLUSION

Advancements in wound care are rapidly expanding. Various treatments for non-healing wounds in paediatric and neonatal patients have been reported, but high tier evidence in these populations is scarce. We hope to shed light on existing evidence regarding the different therapeutic modalities, from debridement techniques and dressing types to tissue substitutes and topical remedies. There have been promising results in many studies to date, but RCTs involving larger sample sizes are necessary, in order to determine the specific role these innovative agents play in paediatric wounds and to identify true safety and efficacy.