Adipose Tissue-Derived Components: From Cells to Tissue Glue to Treat Dermal Damage

Obesity and postoperative flap complications in maxillofacial reconstruction surgery

OBJECTIVES

This single-center retrospective observational study aimed to determine whether obesity is associated with postoperative flap complications following maxillofacial reconstruction. Obesity can increase the risk of postoperative flap complications during autologous breast reconstruction. Therefore, we hypothesized that obesity also affects maxillofacial reconstruction.

STUDY DESIGN

A total of 338 patients (140 males and 198 females) who underwent maxillofacial reconstruction between January 2016 and December 2021 were included. The primary outcome variable was the occurrence of complications. The patients were divided into two groups according to the presence or absence of complications at the recipient site, and risk factors were compared between the two groups. A univariable and multivariable logistic regression analysis was used to investigate the associations between the predictors and outcomes.

RESULTS

Twenty-five (7.40%) of the 338 patients experienced free-flap complications. Those with a greater body mass index (BMI > 25) had the highest complication incidences (13.33%). The multivariable logistic regression analysis showed a higher flap complication risk among patients with obesity than among those with a normal BMI (odds ratio, 3.178; 95% confidence interval: 1.073-9.415, P = .037).

CONCLUSIONS

There was a clear association between BMIs > 25 and flap complication after maxillofacial reconstruction.

A Versatile Skin-Derived Extracellular Matrix Hydrogel-Based Platform to Investigate the Function of a Mechanically Isolated Adipose Tissue Stromal Vascular Fraction

Introduction: To accelerate cutaneous wound healing and prevent scarring, regenerative approaches such as injecting a mechanically derived tissue stromal vascular fraction (tSVF) are currently under clinical and laboratory investigations. The aim of our study was to investigate a platform to assess the interaction between skin-derived extracellular matrix (ECM) hydrogels and tSVF and their effects on their microenvironment in the first ten days of culture. Material and Methods: A tSVF mixed with ECM hydrogel was cultured for ten days. After 0, 3, 5, and 10 days of culture viability, histology, immunohistochemistry, gene expression, and collagen alignment and organization were assessed. Results: The viability analysis showed that tSVF remained viable during 10 days of culture and seemed to remain within their constitutive ECM. The fiber analysis demonstrated that collagen alignment and organization were not altered. No outgrowth of capillaries was observed in (immuno)histochemical staining. The gene expression analysis revealed that paracrine factors TGFB1 and VEGFA did not change and yet were constitutively expressed. Pro-inflammatory factors IL1B and IL6 were downregulated. Matrix remodeling gene MMP1 was upregulated from day three on, while MMP14 was upregulated at day three and ten. Interestingly, MMP14 was downregulated at day five compared to day three while MMP2 was downregulated after day zero. Conclusions: Skin-derived ECM hydrogels appear to be a versatile platform for investigating the function of a mechanically isolated adipose tissue stromal vascular fraction. In vitro tSVF remained viable for 10 days and sustained the expression of pro-regenerative factors, but is in need of additional triggers to induce vascularization or show signs of remodeling of the surrounding ECM. In the future, ECM-encapsulated tSVF may show promise for clinical administration to improve wound healing.

Amino Acid-Based Protein-Mimic Hydrogel Incorporating Pro-Regenerative Lipid Mediator and Microvascular Fragments Promotes the Healing of Deep Burn Wounds

Pro-regenerative lipid mediator 1 (PreM1) is a specialized pro-resolving lipid mediator that promotes wound healing and regenerative functions of mesenchymal stem cells (MSCs), endothelial cells, and macrophages. The healing of third-degree (3°) burns and regenerative functions of MSCs are enhanced by ACgel1, an arginine-and-chitosan-based protein-mimic hybrid hydrogel. Adipose-tissue derived microvascular fragments (MVFs) are native vascularization units and a rich source of MSCs, endothelial cells, and perivascular cells for tissue regeneration. Here we describe an innovative PreM1-MVFs-ACgel1 construct that incorporated PreM1 and MVFs into ACgel1 via optimal design and fabrication. This construct delivered PreM1 to 3°-burn wounds at least up to 7 days-post-burn (dpb), and scaffolded and delivered MVFs. PreM1-MVFs-ACgel1 promoted the healing of 3°-burns in mice, including vascularization and collagen formation. The re-epithelization and closure of 3° burn wounds were promoted by ACgel1, MVFs, PreM1, MVFs-ACgel1, PreM1-ACgel1, or PreM1-MVFs-ACgel1 at certain time-point(s), while PreM1-MVFs-ACgel1 was most effective with 97% closure and 4.69% relative epithelial gap at 13 dpb compared to saline control. The PreM1-ACgel1 and MVFs-ACgel1 also promoted blood vessel regeneration of 3°-burns although PreM1-MVFs-ACgel1 is significantly more effective. These PreM1- and/or MVF-functionalized ACgel1 have nonexistent or minimal graft-donor requirements and are promising adjuvant therapeutic candidates for treating deep burns.

[Research progress of antibacterial hydrogel in treatment of infected wounds]

Objective

To review the research progress of new antibacterial hydrogels in the treatment of infected wounds in the field of biomedicine, in order to provide new methods and ideas for clinical treatment of infected wounds.

Methods

The research literature on antibacterial hydrogels at home and abroad was extensively reviewed in recent years, and the antibacterial hydrogels for the treatment of infected wounds were classified and summarized.

Results

Antibacterial hydrogels can be divided into three categories: inherent antibacterial hydrogels, antibacterial agent release hydrogels, and environmental response antibacterial hydrogels. The advantages and disadvantages of antibacterial materials, antibacterial mechanism, antibacterial ability, and biocompatibility were discussed respectively. Inherent antibacterial hydrogels have the characteristics of wide source, low cost, and simple preparation, but their antibacterial ability is relatively weak. New antimicrobial substances are added to antibacterial agent release hydrogels, such as antimicrobial peptides, metal ions, graphene materials, etc., providing a new therapeutic strategy for alternative antibiotic therapy. On the basis of the antibacterial material, environmental promoting factors such as photothermal effect, pH value, and magnetic force are added to the environmental response antibacterial hydrogels, which synergically enhances the antibacterial ability of the hydrogel, improves the precise regulation function and bionic effect of the hydrogel.

Conclusion

The selection of a variety of materials, the addition of a variety of antibacterial agents, and the effect of various promoting factors make composite hydrogels show multiple characteristics. The development of antibacterial hydrogels that can effectively address practical clinical applications remains a significant challenge. In the future, expanding the application range of antibacterial hydrogels, constructing drug-loaded hydrogels, and developing intelligent hydrogels are still new areas that need to be explored and studied.