Porcine Transgenic, Acellular Material as an Alternative for Human Skin

Optimizing α-Gal Epitope Removal in Porcine Dermal Matrix: Enzyme Selection and Tissue Form Matter

Decellularization does not completely remove the matrix-bound α-Gal epitopes in porcine acellular dermal matrix (pADM), and the presence of residual α-Gal epitopes could elicit adverse immunological reactions and cause potential early failure of xenografts. The present study had evaluated the effectiveness of decellularization and α-galactosidase treatment to eliminate the matrix-bound α-Gal epitopes in pADM, as well as the effect of tissue form (intact pADM vs. microparticle). Decellularization eliminated ∼80% of α-Gal epitopes in porcine dermis, and pADM retained ∼20% of the matrix-bound α-Gal epitopes. While Aspergillus α-galactosidase and Coffea α-galactosidase both hydrolyzed the terminal alpha-galactosyl moiety from oligosaccharides, only Coffea α-galactosidase was effective in eliminating the matrix-bound α-Gal epitopes in intact pADM. Aspergillus α-galactosidase did not work for intact pADM, even at an enzyme activity more than an order of magnitude higher than that of Coffea α-galactosidase used. The different efficacy between Aspergillus α-galactosidase and Coffea α-galactosidase was associated to the accessibility to the matrix-bound α-Gal epitopes in intact pADM. When intact pADM was micronized into fine microparticles, Aspergillus α-galactosidase and Coffea α-galactosidase eliminated the matrix-bound α-Gal epitopes equally well. Thus, the tissue form had significant influence on the efficacy of enzymic cleavage. The findings of the study offer valuable insight for enzyme selection and process development for efficient α-Gal antigen reduction in xenogeneic grafts or tissue scaffolds.

Amnion as an Innovative Antiseptic Carrier: A Comparison of the Efficacy of Allogeneic and Xenogeneic Transplantations in the Context of Burn Therapy

Background and Objectives: The amniotic membrane is widely used in the treatment of chronic wounds, in toxic epidermal necrolysis (TEN), and in the treatment of burns. In our clinical practice, we use amniotic dressings on shallow skin wounds caused by burns. Counteracting infections is an important aspect of working with burn wounds. Therefore, the main goals of this work are to demonstrate the usefulness of amniotic membrane soaked in antiseptics for the prevention of wound infections and to compare the antibacterial efficacy of selected variants of allogeneic and xenogeneic amniotic membrane grafts soaked in specific antiseptic agents. Materials and Methods: The studied material consisted of human and pig placenta. The human and animal amnions were divided in two parts. The first part consisted of amniotic discs placed on rigid mesh discs and preparing the fresh amnion. The second part of the amnion was frozen at a temperature of -80 °C for 24 h. Then, it was radio-sterilized with a dose of 35 kGy. The amniotic discs were placed on rigid mesh to prepare the radiation-sterilized amnion. The amniotic discs were placed in a 12-well plate and immersed in 3 mL of the appropriate antiseptic solutions: Prontosan, Braunol, Borasol, Microdacyn, Octenilin, Sutrisept, and NaCl as a control. The amniotic discs were incubated in antiseptics for 3 h. The microbiological tests were conducted by placing the antiseptic-infused amniotic discs on microbiological media inoculated with hospital strains. Results: The largest average zone of growth inhibition was observed in dressings soaked with Sutrisept, Braunol, and Prontosan. The greatest inhibition of bacterial growth was achieved for radiation-sterilized porcine amnion impregnated with Braunol and Sutrisept, as well as for radiation-sterilized human amnion impregnated with Braunol. Conclusions: Human and porcine amniotic membrane is effective in carrying antiseptics. Radiation-sterilized amnion seems to inhibit the growth of microorganisms better than fresh amnion.

The clinical outcomes of xenografts in the treatment of burn patients: a systematic review and meta-analysis

BACKGROUND

Although autografts are not feasible in patients with extensive burn wounds, allografts and xenografts can be used for temporary coverage. In this systematic review and meta-analysis, we compared the outcomes of xenografts and the standard treatment of burn wounds.

METHODS

International online databases were searched for English articles comparing xenografts with routine treatment in the burn patients. The random-effects model was used to estimate standardized mean differences (SMD) or odds ratios (OR) with a 95% confidence interval (CI).

RESULTS

From a total of 7144 records, 14 studies were included in our review after screening by title and abstracts followed by full-texts. No significant difference in hospital stays was found between the mammalian xenografts and control groups (SMD [95% CI] = - 0.18 [- 0.54-0.18]). The mean number of dressing changes was significantly lower in both mammalian xenografts compared to the controls (SMD [95% CI] = - 1.01 [- 1.61-- 0.41]) and fish xenografts compared to controls (SMD [95% CI] = - 6.16 [- 7.65-- 4.66]). In the fish xenografts, re-epithelialization time was significantly lower compared to controls (SMD [95% CI] = - 1.18 [- 2.23-- 0.14]).

CONCLUSIONS

Xenografts showed a significantly lower number of dressing changes and fish xenografts showed significant benefit in re-epithelialization compared to routine treatment. The beneficial results of xenografts suggest further research in the use of different types of xenografts in patients with extensive burn.

The Role of Lyophilized Xenodermotransplants in Repairing the Atria's Structure and the Peculiarities of Regenerative Processes after Thermal Trauma in an Experiment

The effects of severe burn injuries on the cardiovascular system, specifically the atria and auricles of the heart, were investigated. The potential benefits of using lyophilized xenodermotransplants as a treatment option were also evaluated. The experiments were conducted on adult guinea pigs divided into three groups: intact animals, animals with burns, and animals with burns who underwent early necrectomy followed by wound closure with lyophilized xenodermotransplants. Third-degree burns caused significant ultrastructural changes in atrial cardiomyocytes, leading to long-term destructive changes in the structural components of the atria. However, the use of lyophilized xenodermotransplants had a positive effect on the atrial ultrastructure over time. This study highlights the complex and varied effects of burn injuries on the body and the potential benefits of lyophilized xenodermotransplants in treating severe burn injuries. By preventing destructive changes in the heart and activating regenerative processes, lyophilized xenodermotransplants can improve the condition of the heart after thermal injury. Further research and development in this area are necessary for understanding the potential of lyophilized xenodermotransplants in tissue repair and regeneration.

Comparing the application of various engineered xenografts for skin defects: A systematic review

INTRODUCTION

Xenografts are a now a cornerstone in the management of wound dressings. Promising results were achieved since 1960 in the application of skin substitute for skin defects.

OBJECTIVE

The objective of this study was to evaluate the efficacy of various xenografts.

METHODS

A literature research was conducted using the following query: 'Porcine skin dermatology substitute', 'bovine skin dermatology substitute', 'xenograft skin substitute dermatology', 'xenografts skin defect', 'porcine skin defect', 'bovine skin defect'.

RESULTS

The review yielded 35 articles pertaining to the topic. Main indications for porcine and bovine xenograft application were burn wounds and post-traumatic wounds, respectively. Mean discharge date or length of stay was at the 6th day after porcine application, and the time of graft healing was reported for 33.7% (n = 510) of patients. Promising results were seen with Matriderm and split-thickness skin graft. Most wounds achieved an excellent cosmetic result with full range of motion and a smooth contour appearance. A great variety of tissue substitutes exist, and the choice of graft application should depend on a patient's factors, product availability, wound type, size, and physician's factors.

CONCLUSION

In summary, xenografts are more economic and affordable but have higher risk of infections compared to allografts.

Insights into the use of genetically modified decellularized biomaterials for tissue engineering and regenerative medicine

Various modifications have been performed on biomaterials to improve their applications in tissue engineering and regenerative medicine. However, the challenges of immunogenicity and biocompatibility existed since the application of biomaterials. As a method to solve this problem, the decellularization process removes most living cells from biomaterials to minimize their immunogenicity; and preserves the native structures and compositions that favour cell growth and the subsequent construction of functional tissue. On the other hand, genetic modification of biomaterials aims to achieve specific functions (low immunogenicity, osteogenesis, etc.) or analyse the genetic mechanisms underlying some diseases (cardiac dysfunction, liver fibrosis, etc.). The combination of decellularization and gene modification is highly superior to biomaterials; thus, we must obtain a deeper understanding of these novel biomaterials. In this review, we summarize the fabrication approaches and current applications of genetically modified decellularized biomaterials and then discuss their disadvantages and corresponding future perspectives.

Genetically modified immunomodulatory cell-based biomaterials in tissue regeneration and engineering

To date, the wide application of cell-based biomaterials in tissue engineering and regeneration is remarkably hampered by immune rejection. Reducing the immunogenicity of cell-based biomaterials has become the latest direction in biomaterial research. Recently, genetically modified cell-based biomaterials with immunomodulatory genes have become a feasible solution to the immunogenicity problem. In this review, recent advances and future challenges of genetically modified immunomodulatory cell-based biomaterials are elaborated, including fabrication approaches, mechanisms of common immunomodulatory genes, application and, more importantly, current preclinical and clinical advances. The fabrication approaches can be categorized into commonly used (e.g., virus transfection) and newly developed approaches. The immunomodulatory mechanisms of representative genes involve complicated cell signaling pathways and metabolic activities. Wide application in curing multiple end-term diseases and replacing lifelong immunosuppressive therapy in multiple cell and organ transplantation models is demonstrated. Most significantly, practices of genetically modified organ transplantation have been conducted on brain-dead human decedent and even on living patients after a series of experiments on nonhuman primates. Nevertheless, uncertain biosecurity, nonspecific effects and overlooked personalization of current genetically modified immunomodulatory cell-based biomaterials are shortcomings that remain to be overcome.

Assessment of the Impact of Decellularization Methods on Mechanical Properties of Biocomposites Used as Skin Substitute

This work aimed to assess the impact of acellularization and sterilization methods on the mechanical properties of biocomposites used as a skin substitute. On the basis of the statistical analysis, it was ascertained that the values of the Young modulus for the samples before the sterilization process—only in the cases of substances such as: trypsin, 15% glycerol and dispase—changed in a statistically significant way. In the case of dispase, the Young modulus value before the sterilization process amounted to 66.6 MPa, for trypsin this value equalled 33.9 MPa, whereas for 15% glycerol it was 11 MPa. In the case of samples after the completion of the sterilization process, the analysis did not show any statistically significant differences between the obtained results of Young’s modulus depending on the respective reagents applied. It was confirmed that different methods of acellularization and the process of sterilization effect the alteration of mechanical properties of allogeneic skins. In the case of the decellularization method using SDS (Sodium Dodecyl Sulfate), liquid nitrogen and 85% glycerol the highest values of strain were observed. In the authors’ opinion, it is the above-mentioned methods that should be recommended in the process of preparation of skin substitutes.