Characterization of decellularized ovine small intestine submucosal layer as extracellular matrix‐based scaffold for tissue engineering

The effect of acellular scaffold loaded with Wharton's jelly-derived stem cells and mineral pitch on healing of burn model in rat

Severe burns often result in an exacerbated inflammatory response, which can contribute to further injury. This inflammatory response may lead to an increased risk of infection, multiple organ failure, and death. This study aimed to investigate the potential of reducing inflammation to enhance burn wound healing in rats using ovine's small intestinal submucosa as a carrier for Wharton's jelly mesenchymal stem cells (WJ-MSCs) and Mineral Pitch (MP). A rat burn model was developed, and the animals were divided into four groups: control group: burn, placebo group: scaffold-treated burn, cell experimental group: WJ-MSCs seeded scaffold-treated burn, and cell and MP experimental group: scaffolds loaded with WJ-MSCs and MP-treated burn. After treating the wounds in the relevant groups and sampling them on days 5, 14 and 21, histological and pathological parameters, and the expression of genes involved in angiogenesis and epithelialization were evaluated. The study results revealed several findings in the burn wounds. These included changes in mast cell populations, a decrease in inflammatory neutrophils and lymphocytes, an increase in fibroblasts and blood vessels, and upregulation of angiogenesis and epithelialization genes. These changes collectively contributed to enhanced wound healing in cell and MP experimental group compared to the other groups. The findings suggest that scaffolds loaded with Wharton's jelly-derived stem cells and MP can serve as engineered tools to modulate inflammatory conditions during the burn wound healing process. These interventions can improve burn wound management and promote better outcomes.

The healing effect of a mixture of Arnebia euchroma and animal fat on burn wounds in rats in comparison with sulfadiazine

OBJECTIVE

Thermal burn is a serious cause of morbidity and mortality that affects millions of people worldwide. The aim of this experimental study was to investigate the efficacy of Arnebia euchroma (AE) to treat burn wounds in a rat model.

METHOD

A total of 80 male rats (200-250g) were shaved over the back of the neck (2×3cm2) and a second-degree burn wound was induced at this site under general anaesthesia. The rats were then randomly assigned to one of four groups (each n=20) and the burns were treated daily for 14 days as follows: (1) dressed with animal fat; (2) dressed with sulfadiazine; (3) dressed with a mixture of AE and animal fat; (4) no treatment (control). Five rats from each group were sacrificed on days 3, 5, 9 and 14 post-burn and the wounds were evaluated histologically and immunohistochemically for the expression of interleukin (IL)-1 and IL-6.

RESULTS

There was a significant increase at day 3 and decrease on day 5 samples for the expression of IL-1 in the AE plus fat group and IL-6 in the AE plus fat and sulfadiazine groups, compared to the control and fat treatment groups, respectively. Both AE plus fat and sulfadiazine treatments reduced inflammation and granulation tissue formation by day 5 post-burn, while re-epithelialisation commenced by day 9 post-burn. In addition, burns treated with AE plus fat exhibited keratinised epidermis, associated with regular collagen fibres, compared to moderately dense collagen fibres without vascularisation in the sulfadiazine group.

CONCLUSION

These findings suggested that AE plus fat was superior to sulfadiazine in enhancing burn wound healing in rats.

Decellularized small intestine scaffolds: a potential xenograft for restoration of intestinal perforation

Small intestine perforation is a serious medical condition that requires immediate medical attention. The traditional course of treatment entails resection followed by anastomosis; however, it has complications such as small bowel syndrome (SBS), anastomotic leakage, and fistula formation. Here, a novel strategy is demonstrated, that utilizes the xenogeneic, decellularized goat small intestine as a patch for small intestine regeneration in cases of intestinal perforation. The goat small intestine scaffold underwent sodium dodecyl sulfate decellularization, which revealed consistent, quick, and effective decellularization. Decellularization contributed the least amount of extracellular matrix degradation while maintaining the intestinal architecture. By implanting the decellularized goat small intestine scaffolds (DGSIS) on the chorioallantoic membrane (CAM), no discernible loss of angiogenesis was seen in the CAM region, and this enabled the DGSIS to be evaluated for biocompatibility in ovo. The DGSIS was then xeno-transplanted as a patch on a small intestine perforation rat model. After 30 days post transplant, barium salt used as contrast gastrointestinal X-ray imaging revealed no leakage or obstruction in the small intestine. Histology, scanning electron microscopy, and immunohistochemistry assisted in analyzing the engraftment of host cells into the xeno patch. The xeno-patch expressed high levels of E-cadherin, α-smooth muscle actin (α-SMA), Occludin, Zonnula occluden (ZO-1), Ki 67, and Na+/K+-ATPase. The xeno-patch was consequently recellularized and incorporated into the host without causing an inflammatory reaction. As an outcome, decellularized goat small intestine was employed as a xenograft and could be suitable for regeneration of the perforated small intestine.

Decellularized bladder as scaffold to support proliferation and functionality of insulin-secreting pancreatic cells

Loss in the number or function of insulin-producing β-cells in pancreatic islets has been associated with diabetes mellitus. Although islet transplantation can be an alternative treatment, complications such as apoptosis, ischaemia and loss of viability have been reported. The use of decellularized organs as scaffolds in tissue engineering is of interest owing to the unique ultrastructure and composition of the extracellular matrix (ECM) believed to act on tissue regeneration. In this study, a cell culture system has been designed to study the effect of decellularized porcine bladder pieces on INS-1 cells, a cell line secreting insulin in response to glucose stimulation. Porcine bladders were decellularized using two techniques: a detergent-containing and a detergent-free methods. The resulting ECMs were characterized for the removal of both cells and dsDNA. INS-1 cells were not viable on ECM produced using detergent (i.e., sodium dodecyl sulfate). INS-1 cells were visualized following 7 days of culture on detergent-free decellularized bladders using a cell viability and metabolism assay (MTT) and cell proliferation quantified (CyQUANT™ NF Cell Proliferation Assay). Further, glucose-stimulated insulin secretion and immunostaining confirmed that cells were functional in response to glucose stimulation, as well as they expressed insulin and interacted with the detergent-free produced ECM, respectively.

Comparison Capacity of Collagen Hydrogel and Collagen/Strontium Bioglass Nanocomposite Scaffolds With and Without mesenchymal Stem Cells in Regeneration of Critical Sized Bone Defect in a Rabbit Animal Model

Bone self-healing is limited and requires additional or external intervention to promote and accelerate bone regeneration. Therefore, the aim of this study was to investigate the potential capacity of hydrogel collagen (Co) nanocomposite alone, and in combination with 2% strontium (Co/BGSr2%) in presence of mesenchymal stem cells (MSCs) in full-thickness bone defect regeneration in the rabbit animal model. A total of 72 New Zealand white rabbits were randomly divided in 6 groups of 12 rabbits with full-thickness bone defect. In five groups, the bone defect was treated with MSC, Co, Co/BGSr2%, Co + MSCs, and Co/BGSr2% + MSCs. No treatment was done in the control group. The treatments were assessed radiographically, histopathologically, and immunohistochemically on days 14, 28, 42, and 56 post-treatment. The highest radiographical and histological scores were belonged to the Co/BGSr2% + MSC followed by Co + MSCs, Co/BGSr2%, Co, MSC, and the control groups. The highest and lowest mean expression level of osteocalcin was detected in the Co/BGSr2% + MSC and control groups by 28th dayof post-implantation, respectively. In contrast, the highest and lowest mean expression level of osteocalcin on day 56 post-implantation was belonged to the control and Co/BGSr2% + MSC, respectively. The Co/BGSr2% nanocomposite scaffold seeded with MSC can accelerate bone regeneration resulted from osteoblastic production of osteocalcin protein. Therefore, collagen hydrogel combined with 2% strontium in nanocomposite form is a suitable candidate scaffold for bone tissue engineering.

Decellularization for the retention of tissue niches

Decellularization of natural tissues to produce extracellular matrix is a promising method for three-dimensional scaffolding and for understanding microenvironment of the tissue of interest. Due to the lack of a universal standard protocol for tissue decellularization, recent investigations seek to develop novel methods for whole or partial organ decellularization capable of supporting cell differentiation and implantation towards appropriate tissue regeneration. This review provides a comprehensive and updated perspective on the most recent advances in decellularization strategies for a variety of organs and tissues, highlighting techniques of chemical, physical, biological, enzymatic, or combinative-based methods to remove cellular contents from tissues. In addition, the review presents modernized approaches for improving standard decellularization protocols for numerous organ types.

Development of decellularization protocol for caprine small intestine submucosa as a biomaterial

Decellularized animal tissues have been proven to be promising biomaterials for various tissue engineering (TE) applications. Among various animal tissues, small intestine submucosa (SIS) has gained attention of many researchers due to its easy availability from the abattoir waste, excellent physicochemical and biological characteristics of a good biomaterial. In this study, Caprine SIS was decellularized to get decellularized caprine SIS (DG-SIS). For decellularization, several physical, chemical and enzymatic protocols have been described in the literature. To optimize the decellularization of caprine SIS, several decellularization protocol (DP), including an in-house developed by us, had been attempted, and effect of the different DPs on the obtained DG-SIS were assessed in terms of decellularization, physiochemical and biological properties. All the DPs differ in terms of decellularization, but three DPs where ionic detergent like sodium dodecyl sulphate (SDS) has been used, largely affect the native composition (e.g. glycosaminoglycans (GAGs)), biological properties and other physiochemical properties of the G-SIS as compared to the DP that uses hypertonic solution of potassium iodide (KI) and non-ionic detergent (TritonX-100). The obtained DG-SISs were fibrous, hemocompatible, biocompatible, hydrophilic, biodegradable and exhibited significant antibacterial activity. Therefore, the DG-SIS will be a prospective biomaterial for TE applications.

Decellularization of Small Intestinal Submucosa

Small intestinal submucosa (SIS) is the most studied extracellular matrix (ECM) for repair and regeneration of different organs and tissues. Promising results of SIS-ECM as a vascular graft, led scientists to examine its applicability for repairing other tissues. Overall results indicated that SIS grafts induce tissue regeneration and remodeling to almost native condition. Investigating immunomodulatory effects of SIS is another interesting field of research. SIS can be utilized in different forms for multiple clinical and experimental studies. The aim of this chapter is to investigate the decellularization process of SIS and its common clinical application.

Curcumin in decellularized goat small intestine submucosa for wound healing and skin tissue engineering

Biomaterials derived from extracellular matrices (ECMs) were extensively used for skin tissue engineering and wound healing. ECM is a complex network of biomolecules (e.g., proteins), which provide organizational support to cells for growth. Thus, ECM could be an ideal biomaterial for fabricating the scaffold. However, oxidative stress and biofilm formation at the wound site remains a major challenge that could be neutralized using herbal ingredients (e.g., curcumin). In this study, ECM was extracted from the biowaste of the goat abattoir by using decellularization. The goat small intestine submucosa (G-SIS) is decellularized to obtain the decellularized G-SIS (DG-SIS) and curcumin (in different concentrations) was incorporated in the DG-SIS to fabricate curcumin-embedded DG-SIS scaffolds. Changes brought by increasing the concentrations of the curcumin in DG-SIS were observed in various properties, including free radical scavenging and antibacterial properties. Results depicted that the scaffolds are porous, biodegradable, biocompatible, antibacterial, and hydrophilic and showed sustained release of curcumin. Besides, it showed free radicals scavenging property. The porosity and hydrophilicity of the scaffolds were decreased with an increase in the curcumin content. However, biodegradability, free radical scavenging, biocompatibility, and antibacterial properties of the scaffolds increased with an increase in the curcumin content. The DG-SIS scaffold containing 1 wt % of curcumin may be a potential biomaterial for wound-healing and skin tissue engineering.

Evaluating the effects of vacuum on the microstructure and biocompatibility of bovine decellularized pericardium

The aim of this study was evaluating the effects of vacuum on microstructure and biocompatibility of bovine decellularized pericardium. So the bovine pericardia were decellularized and then the vacuum was applied for two periods of time; 90 and 180 min. DNA, glucose amino glycan, collagen and elastin content assay, scanning electron microscopy (SEM) examination, hematoxylin and eosin (H&E) and Masson's trichrome stainings performed to evaluate microstructure of tissues. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test, subcutaneous implantation, and tensile test were used to assay biocompatibility and mechanical properties of decellularized tissues. The results showed that applying vacuum reduced residual DNA significantly. Vacuum after 180 min reduced more residual DNA. There were no significant differences in the content of glucose amino glycan (GAG), collagen, and elastin between the vacuumed and control groups. SEM examination was revealed that vacuum for 180 min increased pore size and porosity more than 90 min and control groups. H&E and Masson's trichrome stainings revealed extracellular matrix preservation after decellularization in all groups. Cell viability was increased in vacuumed samples significantly after 72 h in vaccumed samples. H&E staining and tensile test after implantation of tissues were showed less inflammation in the vacuum applied tissues and increased durability. The vacuum increased DNA removal, pore size, porosity, and biocompatibility in vitro and in vivo and durability of bovine decellularized pericardium in vivo. Considering the important role of time, more studies should be performed to optimize time, intensity, and method of application of vacuum in decellularization of different tissues as well as bovine pericardium.

The useful agent to have an ideal biological scaffold

Tissue engineering which is applied in regenerative medicine has three basic components: cells, scaffolds and growth factors. This multidisciplinary field can regulate cell behaviors in different conditions using scaffolds and growth factors. Scaffolds perform this regulation with their structural, mechanical, functional and bioinductive properties and growth factors by attaching to and activating their receptors in cells. There are various types of biological extracellular matrix (ECM) and polymeric scaffolds in tissue engineering. Recently, many researchers have turned to using biological ECM rather than polymeric scaffolds because of its safety and growth factors. Therefore, selection the right scaffold with the best properties tailored to clinical use is an ideal way to regulate cell behaviors in order to repair or improve damaged tissue functions in regenerative medicine. In this review we first divided properties of biological scaffold into intrinsic and extrinsic elements and then explain the components of each element. Finally, the types of scaffold storage methods and their advantages and disadvantages are examined.

A preliminary study on the development of a novel biomatrix by decellularization of bovine spinal meninges for tissue engineering applications

Here, we aim at developing a novel biomatrix from decellularized bovine spinal meninges for tissue engineering and regenerative medicine applications. Within this concept, the bovine spinal meninges were decellularized using 1% Triton X-100 for 48 h, and residual nuclear content was determined with double-strand DNA content analysis and agarose gel electrophoresis. The major matrix components such as sulfated GAGs and collagen before and after the decellularization process were analyzed with DMMB, hydroxyproline assay and SDS-PAGE. Subsequently, the native bovine spinal meninges (nBSM) and decellularized BSM (dBSM) were physiochemically characterized via ATR-FTIR spectroscopy, TGA, DMA and tensile strength test. The dsDNA content in the nBSM was 153.39 ± 53.93 ng/mg dry weight, versus in the dBSM was 39.47 ± 4.93 ng/mg (n = 3) dry weight and DNA fragments of more than 200 bp in length were not detected in the dBSM by agarose gel electrophoresis. The sulfated GAGs contents for nBSM and dBSM were observed to be 10.87 ± 1.2 and 11.42 ± 2.01 μg/mg dry weight, respectively. The maximum strength of dBSM in dry and wet conditions was found to be 19.67 ± 0.21 MPa and 13.97 ± 0.17 MPa, while nBSM (dry) was found to be 26.26 ± 0.28 MPa. MTT, SEM, and histology results exhibited that the cells attached to the surface of dBSM, and proliferated on the dBSM. In conclusion, the in vitro preliminary study has demonstrated that the dBSM might be a proper and new bioscaffold for tissue engineering and regenerative medicine applications.

Induced cell migration based on a bioactive hydrogel sheet combined with a perfused microfluidic system

Endothelial cell migration is a crucial step in the process of new blood vessel formation-a necessary process to maintain cell viability inside thick tissue constructs. Here, we report a new method for maintaining cell viability and inducing cell migration using a perfused microfluidic platform based on collagen gel and a gradient hydrogel sheet. Due to the helpful role of the extracellular matrix components in cell viability, we developed a hydrogel sheet from decellularized tissue (DT) of the bovine heart and chitosan (CS). The results showed that hydrogel sheets with an optimum weight ratio of CS/DT = 2 possess a porosity of around 75%, a mechanical strength of 23 kPa, and display cell viability up to 78%. Then, we immobilized a radial gradient of vascular endothelial growth factor (VEGF) on the hydrogel sheet to promote human umbilical vein endothelial cell migration. Finally, we incorporated the whole system as an entirety on the top of the microfluidic platform and studied cell migration through the hydrogel sheet in the presence of soluble and immobilized VEGF. The results demonstrated that immobilized VEGF stimulated cell migration in the hydrogel sheet at all depths compared with soluble VEGF. The results also showed that applying a VEGF gradient in both soluble and immobilized states had a significant effect on cell migration at limited depths (<100 μm). The main finding of this study is a significant improvement in cell migration using an in vivo imitating, cost-efficient and highly reproducible platform, which may open up a new perspective for tissue engineering applications.

Exploiting crosslinked decellularized matrix to achieve uterus regeneration and construction

Decellularized extracellular matrix (dECM) has been considered as a promising scaffold in xenotransplantation, yet natural tissue dECM is often mechanically weak and rapidly degraded, compromising the outcomes. How to restore the mechanical strength and optimise the in vivo degradation, but maintain the microstructure and maximumly suppress the immune rejection, remains challenging. For this aim, we prepared and characterised various crosslinked decellularized rabbit uterus matrix (dUECM) and evaluated in vivo performance after uterus xenotransplantation from rabbit to rat. Naturally derived genipin (GP) and procyanidins (PC) were chosen to crosslink the dUECM, producing significant mechanical enhanced crosslinked-dUECM along with prolonged enzymatic degradation rate. Xenogeneic subcutaneous graft studies revealed that PC- and GP-crosslinked dUECM experienced significant cell infiltration and caused low immune reactions, indicating the desired biocompatibility. In vivo transplantation of GP- and PC-crosslinked dUECM to a uterus circular excised rat yielded excellent recellularization ability and promoted uterus regeneration after 90 days. While the reconstruction efficacy of crosslinked dUECM is highly depended on the crosslinking degree, crosslinking condition must be carefully evaluated to balance the role of crosslinked dECM in mechanical and biological support for tissue regeneration promotion.

CD93 hematopoietic stem cells improve diabetic wound healing by VEGF activation and downregulation of DAPK-1

Diabetes is associated with numerous complications, such as diabetic skin wounds or ulcerations. The aim of this study was to evaluate experimentally the effectiveness of applying polycaprolactone (PCL)-gelatin scaffold, with or without rat CD93 hematopoietic stem cells (HSCs), in diabetic wound healing in a rat model. CD93 HSCs were aseptically isolated from rat bone marrow using fluorescent activated cell sorting (FACS) method and FACS-SORTER. A total of 25 Wistar rats were divided into five groups including Group I (sham, nondiabetic, and wound covered only with sterile dressing), II (control, diabetic rat), III (CD93 HSCs alone), IV (PCL-gelatin scaffold), and V (CD93 HSCs+PCL-gelatin scaffold). Animals were killed on Days 7, 14, or 28 posttreatment and histological sections were blindly evaluated by two expert pathologists. Death-associated protein kinase 1 (DAPK-1) gene and vesicular endothelial growth factors (VEGF) protein expression were evaluated using reverse transcription-polymerase chain reaction and western blot, respectively. The thickest and the thinnest epidermises microscopically were belonged to CD93+HSCs+scaffold and the control group, respectively. The growth rate of the epidermis and adnexal epithelia was the highest in both the cell and cell+scaffold groups. Evaluation of the protein expression level of VEGF indicated that the expression levels of this growth factor were the most on Day 7 posttreatment in sham, HSCs alone, and HSCs cell+scaffold groups. While the lowest expression levels of this growth factor was detected in the control and scaffold groups. The gene expression level of DAPK-1 on Day 7 posttreatment was higher than that of the Day 14 posttreatment in all groups. The highest and lowest gene expression levels of DAPK-1 belonged to control and sham groups, respectively. According to our findings, CD93 HSCs offer new prospects for the treatment of diabetic ulcers and concomitant application of these cells with PCL-gelatin nanofiber scaffold significantly improves diabetic wound treatment.

ECM in Differentiation: A Review of Matrix Structure, Composition and Mechanical Properties

Stem cell regenerative potential owing to the capacity to self-renew as well as differentiate into other cell types is a promising avenue in regenerative medicine. Stem cell niche not only provides physical scaffolding but also possess instructional capacity as it provides a milieu of biophysical and biochemical cues. Extracellular matrix (ECM) has been identified as a major dictator of stem cell lineage, thus understanding the structure of in vivo ECM pertaining to specific tissue differentiation will aid in devising in vitro strategies to improve the differentiation efficiency. In this review, we summarize details about the native architecture, composition and mechanical properties of in vivo ECM of the early embryonic stages and the later adult stages. Native ECM from adult tissues categorized on their origin from respective germ layers are discussed while engineering techniques employed to facilitate differentiation of stem cells into particular lineages are noted. Overall, we emphasize that in vitro strategies need to integrate tissue specific ECM biophysical cues for developing accurate artificial environments for optimizing stem cell differentiation.

Evaluation of vacuum washing in the removal of SDS from decellularized bovine pericardium: method and device description

Aims

The aim of this study was to present a new method for removing Sodium dodecyl sulfate (SDS) detergent from decellularized bovine pericardium using vacuum.

Materials and Methods

The cows' pericardia were collected and decellularized. The samples were incubated with SDS1% for 48 h at 40 °C. To perform vacuum washing (VW: negative pressure was used to wash and remove detergents), every decellularized tissue was cut in 75mm diameter and fixed via a stainless-steel ring with 60mm diameter in the center of filtration Buchner Funnel which was connected to glass filtration flask The system was connected to a vacuum pump by a hose, and a negative pressure of -100 mmHg was applied for 15 min. Then, the samples were shaken and washed at 40-rpm in 100 ml of distilled water for 45 min. This process was repeated for samples of each group (6 times for sample VW6h, 12 times for sample VW12h, and 24 times for sample VW24h). At the end of every cycle, the effluent was collected to take a sample for SDS measurement. The normal washing (NW) group containing distilled water (NWd) and PBS (Phosphate buffered saline) (NWp) were used to wash and remove detergents. SDS measurements, MTT Assay, histological and tensile test, to compare two methods were used.

Results

The highest SDS in the effluent was in groups VW12h and VW24h (P ≤ 0.001) and the lowest residual SDS in scaffold was in two groups of VW12h and VW24h (P ≤ 0.001). MTT assay showed that cell survival in the VW12h and VW24h groups was higher than other groups and there' was no significant difference between cell survival in the VW12h and VW24h groups. Histological study showed destruction of tissue in the VW24h group. The results of the tensile test were shown that the native group had the highest module and the lowest amount was the VW24h sample which was reported with P ≤ 0.001 significance for all groups.

Conclusion

VW12h can be used as an effective method for SDS removal from decellularized pericardium which morphologically demonstrated a good structure in ECM.

Recent development and biomedical applications of decellularized extracellular matrix biomaterials

Decellularized matrix (dECM) is isolated extracellular matrix of tissues from its original inhabiting cells, which has emerged as a promising natural biomaterial for tissue engineering, aiming at support, replacement or regeneration of damaged tissues. The dECM can be easily obtained from tissues/organs of various species by adequate decellularization methods, and mimics the structure and composition of the native extracellular matrix, providing a favorable cellular environment. In this review, we summarize the recent developments in the preparation of dECM materials, including decellularization, crosslinking and sterilization. Also, we cover the advances in the utilization of dECM biomaterials in regeneration medicine in pre-clinic and clinical trials. Moreover, we highlight those emerging medical benefits of dECM beyond tissue engineering, such as cell transplantation, in vitro/in vivo model and therapeutic cues delivery. With the advances in the preparation and broader application, the dECM biomaterials could become the gold scaffold and pharmaceutical excipients in medical sciences.