Primary chicken embryo fibroblasts seeded acellular dermal matrix (3-D ADM) improve regeneration of full thickness skin wounds in rats

Polysaccharide- and protein-based hydrogel dressings that enhance wound healing: A review

Hydrogels can possess desired biochemical and mechanical properties, excellent biocompatibility, satisfactory biodegradability, and biological capabilities that promote skin repair, making them ideal candidates for skin healing dressings. Polysaccharides, such as chitosan, hyaluronic acid and sodium alginate as well as proteins, including gelatin, collagen and fibroin proteins, are biological macromolecules celebrated for their biocompatibility and biodegradability, are at the forefront of innovative hydrogel dressing development. This work first summarizes the skin wound healing process and its influencing factors, and then systematically articulates the multifunctional roles of hydrogels based on biological macromolecules (polysaccharides and proteins) as dressing in addressing bacterial infection, hemorrhage and inflammation during wound healing. Furthermore, this review explores the potential of these hydrogels as vehicles for combination therapy, by incorporating growth factors or stem cells. Finally, the article offers insights into future directions of such hydrogels in wound repair field.

Comparative evaluation of two different xenogenic acellular matrices on full-thickness skin wound healing

OBJECTIVE

The purpose of the study was to compare the healing potential of bubaline small intestinal matrix (bSIM) and fish swim bladder matrix (FSBM) on full-thickness skin wounds in rabbits.

METHOD

Four full-thickness skin wounds (each 20×20mm) were created on the dorsum of 18 rabbits that were divided into three groups based on treatment: untreated sham control (I), implanted with double layers of bSIM (II) and implanted with double layers of FSBM (III). Macroscopic, immunologic and histologic observations were made to evaluate wound healing.

RESULTS

Gross healing progression in the bSIM and FSBM groups showed significantly (p<0.05) less wound contraction compared with the sham group. The IgG concentration in rabbit sera was significantly (p<0.05) lower in the FSBM group compared with the bSIM group by enzyme-linked immunosorbent assay. The stimulation index of peripheral blood lymphocytes was significantly (p<0.05) lower in the FSBM group compared with the bSIM group by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Implantation of FSBM resulted in improved re-epithelialisation, neovascularisation and fibroplasia.

CONCLUSION

The FSBM is a more effective dermal substitute when compared with the bSIM for full-thickness skin wound repair in rabbit.

The Effect of Fetal Bovine Acellular Dermal Matrix Seeded with Wharton's Jelly Mesenchymal Stem Cells for Healing Full-Thickness Skin Wounds

The treatment of full-thickness skin wounds is a problem in the clinical setting, as they do not heal spontaneously. Extensive pain at the donor site and a lack of skin grafts limit autogenic and allogeneic skin graft availability. We evaluated fetal bovine acellular dermal matrix (FADM) in combination with human Wharton's jelly mesenchymal stem cells (hWJ-MSCs) to heal full-thickness skin wounds. FADM was prepared from a 6-month-old trauma-aborted fetus. WJ-MSCs were derived from a human umbilical cord and seeded on the FADM. Rat models of full-thickness wounds were created and divided into three groups: control (no treatment), FADM, and FADM-WJMSCs groups. Wound treatment was evaluated microscopically and histologically on days 7, 14, and 21 post-surgery. The prepared FADM was porous and decellularized with a normal range of residual DNA. WJ-MSCs were seeded and proliferated on FADM effectively. The highest wound closure rate was observed in the FADM-WJMSC group on days 7 and 14 post-surgery. Furthermore, this group had fewer inflammatory cells than other groups. Finally, in this study, we observed that, without using the differential cell culture media of fibroblasts, the xenogeneic hWJSCs in combination with FADM could promote an increased rate of full-thickness skin wound closure with less inflammation.

Histologic characterization of orbicularis oris muscle with a new acellular dermal matrix grafts in a rabbit model

Muscular dysplasia is the key factor in influencing surgical outcomes in patients with cleft lip/palate. In this research, we attempted to evaluate a new acellular dermal matrix (ADM) as a substitute for reconstruction of the orbicularis oris muscle with growth factors such as Insulin-Like Growth Factor I (IGF-I), vascular endothelial growth factor (VEGF) in a rabbit model. 30 male New Zealand Rabbits (2-3 m, 1700-2000 g) were divided into four groups as follows; a group in which the orbicularis oris muscle of the upper lip was implanted with ADM, a group in which the orbicularis oris muscle of the upper lip was implanted with ADM + IGF-I + VEGF, a group in which the upper lip was operated without implantation of an ADM scaffold, and a normal upper lip for comparison. Macroscopic observation, histological evaluation, and immunohistochemistry were employed to evaluate levels of the muscle regeneration, vascularization, and inflammation at 1, 2, 4, 6, and 12 weeks after the operation. All wounds healed well without infection, immune rejection and so on. Histological evaluation showed that ADM was totally degraded and replaced by connective tissue. The area in which the ADM scaffold was coated with growth factors show a significant increase in the formation of new myofibers after injury, and the vascularization improved compared to the control group and the normal group. In regard to the degrees of inflammation, there were no notable differences among the groups. In conclusion, Our study indicated that ADM grafts combined with IGF-I and VEGF have potential advantages in alleviating muscular dysplasia in cleft lip treatment.

Decellularization of caprine esophagus using fruit pericarp extract of Sapindus mukorossi

Biological detergents like sodium deoxycholate, sodium dodecyl sulphate and Triton X-100 impairs the collagenous and non-collagenous proteins, glycosaminoglycans and growth factors. Further, certain chemical and enzymes are responsible for residual cytotoxicity in the decellularized extracellular matrix. The main focus of this study was to explore the decellularization property of soap nut pericarp extract (SPE) for development of decellularized tubular esophageal scaffold. For this 2.5, 5.0 and 10% concentrations of SPE were used for decellularization of caprine esophageal tissues. Histological analysis of hematoxylin and eosin and Masson's trichrome stained tissue samples confirmed decellularization with preservation of extracellular matrix microarchitecture. Scanning electron microscopic images of luminal surface of decellularized esophageal matrix showed randomly oriented collagen fibres with large interconnected pores and cells were absent. However, the external surface was more textured with fibrous structures and collagen fibres were well preserved. DAPI stained decellularized tissues revealed complete removal of nuclear components, verified by DNA content measurement and SDS-PAGE. The FTIR spectra of decellularized esophagus shows absorption peaks of amide A, B, I, II and III. Elastic modulus of the decellularized esophagus scaffolds increased (P > 0.05) as compared to native tissues. Histological and scanning electron microscopic evaluation of in vitro seeded scaffolds showed attachment and growth of primary chicken embryo fibroblasts over and within the decellularized scaffolds. It was concluded that 5% SPE is ideal for preparation of cytocompatible decellularized caprine esophageal scaffold with well-preserved extracellular matrix architecture and, may be used as an alternative to biological detergents and other chemicals.

Development of decellularized aortic scaffold for regenerative medicine using Sapindus mukorossi fruit pericarp extract

The aim of this study is to develop a novel decellularization method using aqueous extract of soap nut pericarp (SPE) and its evaluation using hematoxylin-eosin staining, scanning electron microscopy, diamidino-2-phenylindol (DAPI) staining, mechanical testing, sodium dodecyl sulfate polyacrylamide gel electrophoresis and DNA quantification. The presently available decellularization agent raises some concerns due to the potential for presence of residual cytotoxic agents in the extracellular matrix. Histological analysis of hematoxylin and eosin and masson's trichrome stained processed aortic samples shows complete decellularization with preservation of extracellular matrix microarchitecture at 120 h. Further, staining of tissue samples with DAPI demonstrates complete removal of DNA fragments. Quantitative evaluation of DNA in the decellularized aorta tissues demonstrated a significant (P < 0.01) decrease in DNA content as compared to native tissues. Collagen quantification assay indicate no significant (P> 0.05) difference in its content between native and decellularized caprine aorta. Tensile strength of the decellularized scaffolds decreased non-significantly (P > 0.05) when compared to native tissues. There was no significant (P > 0.05) difference in young's modulus of elasticity, stiffness and stretch ratio between native aortic tissues and decellularized aortic scaffolds. Histological and scanning electron microscopic examination of in vitro cultured scaffold demonstrated the cell viability and proliferation of primary chicken embryo fibroblasts. SPE treatment is thus capable of producing cytocompatible decellularized caprine aorta scaffold with preservation of extracellular matrix architecture for vascular tissue engineering and could be applied widely as one of the decellularization agent.

Preparation, characterization, and xenotransplantation of the caprine acellular dermal matrix

BACKGROUND

Caprine skin is a promising biomaterial for tissue-engineering applications. However, tissue processing is required before its xenogenic use.

AIMS

Therefore, the purpose of this study was to evaluate the structural integrity and biocompatibility of the caprine skin after de-epithelialization, using sodium chloride (NaCl) and trypsin solutions, followed by de-cellularization using sodium dodecyl sulfate (SDS) solution.

MATERIALS & METHODS

The caprine skin was de-epithelialized using NaCl (2-4 mol/L) and trypsin (0.25%-0.5%) followed by the treatment of SDS (1%-4%) solution over a period of time. Acellularity of the prepared matrix was confirmed histologically and characterized by appropriate staining, scanning electron microscopy (SEM), DNA quantification, and Fourier-transform infrared (FTIR) spectroscopy. The caprine acellular dermal matrix (CADM) was used for the repair of spontaneously occurring abdominal hernia in ten buffaloes. The biocompatibility of the CADM was evaluated using clinical, hematological, biochemical, and anti-oxidant parameters.

RESULTS

Histologically, the skin treated with 0.25% trypsin in 4 mol/L NaCl for 8 hours resulted in complete de-epithelialization. Further treatment with 2% SDS for 48 hours demonstrated complete acellularity and orderly arranged collagen fibers. The SEM confirmed a preservation of collagen arrangement within CADM. The DNA content was significantly (P < .05) lower in CADM (46.20 ± 7.94 ng/mg) as compared to fresh skin (662.56 ± 156.11 ng/mg) indicating effective acellularity. The FTIR spectra showed characteristic collagen peaks of amide A, amide B, amide I, amide II, and amide III in CADM. All the 10 animals recovered uneventfully and remained sound. Hematological, biochemical, and anti-oxidants findings were unremarkable.

CONCLUSION

Results indicated the acceptance and biocompatibility of the xenogenic caprine acellular dermal matrix for abdominal hernia repair in buffaloes without complications.

In situ gelation of rhEGF-containing liquid crystalline precursor with good cargo stability and system mechanical properties: a novel delivery system for chronic wounds treatment

The objective of this study was to develop a novel delivery system for recombinant human epidermal growth factor (rhEGF) for chronic wound treatment. Such a delivery system should be of good cargo stability and system mechanical properties in order to guarantee a satisfactory wound-healing effect. rhEGF-containing lyotropic liquid crystalline precursors (rhEGF-LLCPs) with in situ gelation capability were considered as a promising candidate to achieve this aim. Various properties of the optimal formulations (rhEGF-LLCP1 and rhEGF-LLCP2) were characterized, including apparent viscosity, gelation time, in vitro release and phase behavior. The stability of rhEGF and system mechanical properties (i.e. mechanical rigidity and bioadhesive force) were verified. Interestingly, rhEGF-LLCP2 with a larger internal water channel diameter exhibited faster release rate in vitro and then better bioactivity in Balb/c 3T3 and HaCaT cell models. Moreover, rhEGF-LLCP2 showed distinct promotion effects on wound closure, inflammatory recovery and re-epithelization process in Sprague-Dawley rat models. In conclusion, rhEGF-LLCP emerged as a prospective candidate to preserve the stability and enhance the wound-healing effect of rhEGF, which might serve as a new delivery system for chronic wound therapies.

Evaluation of the efficacy of cell and micrograft transplantation for full-thickness wound healing

BACKGROUND

Skin grafting is the current standard of care in the treatment of full-thickness burns and other wounds. It is sometimes associated with substantial problems, such as poor quality of the healed skin, scarring, and lack of donor-site skin in large burns. To overcome these problems, alternative techniques that could provide larger expansion of a skin graft have been introduced over the years. Particularly, different cell therapies and methods to further expand skin grafts to minimize the need for donor skin have been attempted. The purpose of this study was to objectively evaluate the efficacy of cell and micrograft transplantation in the healing of full-thickness wounds.

MATERIALS AND METHODS

Allogeneic cultured keratinocytes and fibroblasts, separately and together, as well as autologous and allogeneic skin micrografts were transplanted to full-thickness rat wounds, and healing was studied over time. In addition, wound fluid was collected, and the level of various cytokines and growth factors in the wound after transplantation was measured.

RESULTS

Our results showed that both autologous and allogeneic micrografts were efficient treatment modalities for full-thickness wound healing. Allogeneic skin cell transplantation did not result in wound closure, and no viable cells were found in the wound 10 d after transplantation.

CONCLUSIONS

Our study demonstrated that allogeneic micrografting is a possible treatment modality for full-thickness wound healing. The allografts stayed viable in the wound and contributed to both re-epithelialization and formation of dermis, whereas allogeneic skin cell transplantation did not result in wound closure.

Biomaterial Scaffolds for Reproductive Tissue Engineering

The reproductive system usually involves gamete producing gonads, a series of specialized ducts, accessory glands and the external genitalia. Despite there are many traditional methods such as hormonal and surgical approaches, at present no effective treatments exist to help patients suffering from serious diseases of reproductive system, including congenital and acquired abnormalities, malignant tumor, traumatic, infectious etiologies, inflammation and iatrogenic injuries. Tissue engineering holds promise for reproductive medicine through the development of biological alternative. Till now, a diverse range of biomaterials have been utilized as suitable substrates to match both the mechanical and biological context of reproductive tissues. The current review will focus mainly on the applications of biomaterial scaffolds and their major achievements in each region of reproductive systems.

Bubaline Cholecyst Derived Extracellular Matrix for Reconstruction of Full Thickness Skin Wounds in Rats

An acellular cholecyst derived extracellular matrix (b-CEM) of bubaline origin was prepared using anionic biological detergent. Healing potential of b-CEM was compared with commercially available collagen sheet (b-CS) and open wound (C) in full thickness skin wounds in rats. Thirty-six clinically healthy adult Sprague Dawley rats of either sex were randomly divided into three equal groups. Under general anesthesia, a full thickness skin wound (20 × 20 mm(2)) was created on the dorsum of each rat. The defect in group I was kept as open wound and was taken as control. In group II, the defect was repaired with commercially available collagen sheet (b-CS). In group III, the defect was repaired with cholecyst derived extracellular matrix of bovine origin (b-CEM). Planimetry, wound contracture, and immunological and histological observations were carried out to evaluate healing process. Significantly (P < 0.05) increased wound contraction was observed in b-CEM (III) as compared to control (I) and b-CS (II) on day 21. Histologically, improved epithelization, neovascularization, fibroplasia, and best arranged collagen fibers were observed in b-CEM (III) as early as on postimplantation day 21. These findings indicate that b-CEM have potential for biomedical applications for full thickness skin wound repair in rats.