The effect of Wharton's jelly-derived stem cells seeded/boron-loaded acellular scaffolds on the healing of full-thickness burn wounds in the rat model.

Burn wounds are the most destructive and complicated type of skin or underlying soft tissue injury that are exacerbated by a prolonged inflammatory response. Several cell-based therapeutic systems through the culturing of potent stem cells on modified scaffolds have been developed to direct the burn healing challenges. In this context, a new regenerative platform based on boron (B) enriched-acellular sheep small intestine submucosa (AOSIS) scaffold was designed and used as a carrier for mesenchymal stem cells derived from Wharton's jelly (WJMSCs) aiming to promote the tissue healing in burn-induced rat models. hWJMSCs have been extracted from human extra-embryonic umbilical cord tissue. Thereafter, 96 third-degree burned Wistar male rats were divided into 4 groups. The animals that did not receive any treatment were considered as group A (control). Then, group B was treated just by AOSIS scaffold, group C was received cell-seeded AOSIS scaffold (hWJMSCs-AOSIS), and group D was covered by boron enriched-cell-AOSIS scaffold (B/hWJMSCs-AOSIS). Inflammatory factors, histopathological parameters, and the expression levels of epitheliogenic and angiogenic proteins were assessed on 5, 14 and 21 d post-wounding. Application of the B/hWJMSCs-AOSIS on full-thickness skin-burned wounds significantly reduced the volume of neutrophils and lymphocytes at day 21 post-burning, whilst the number of fibroblasts and blood vessels enhanced at this time. In addition, molecular and histological analysis of wounds over time further verified that the addition of boron promoted wound healing, with decreased inflammatory factors, stimulated vascularization, accelerated re-epithelialization, and enhanced expression levels of epitheliogenic genes. In addition, the boron incorporation amplified wound closure via increasing collagen deposition and fibroblast volume and activity. Therefore, this newly fabricated hWJMSCs/B-loaded scaffold can be used as a promising system to accelerate burn wound reconstruction through inflammatory regulation and angiogenesis stimulation.

Experimental and numerical study on the performance of printed alginate/hyaluronic acid/halloysite nanotube/polyvinylidene fluoride bio-scaffolds.

The growing usage of printed bio scaffolds in the field of regenerative medicine has made this field very important in biomedical engineering. In this regard, three-dimensional printing (3D) technique needs bio-materials with higher mechanical and biological performance. The biomaterials with high mechanical performance beside its bio compatibility are limited. A novel bio-material made of Alginate, Hyaluronic acid, Halloysite Nanotube and Polyvinylidene Fluoride was used and characterized for printing cartilage bio scaffolds through numerical studies. CaCl2 was used for crosslinking of biomaterial. Scanning Electron Microscopy, mechanical tests (tensile and compressive test), MTT assay were conducted for evaluating this novel biomaterial. Different structures of bio material were simulated for numerical studies. The numerical study was performed in ANSYS 18 using three parameter Mooney-Rivlin model. According to experimental and numerical results, Halloysite Nanotube increases the tensile and compressive strength of biomaterial up to 47%. Results show that biomaterial have good mechanical performance due to mechanical forces required for cartilage bio scaffolds besides its high biological performance. Polyvinylidene fluoride reduces the mechanical performance while increasing the cell viability. MTT assay results performed on day 0, day 2 and day 6 show increase in cell number to be about twice for biomaterial containing 40 mg/ml alginate, 40 mg/ml halloysite nanotube, 10 mg/ml hyaluronic acid and 1 w/v Polyvinylidene fluoride. Numerical simulation shows high mechanical performance of bio material in different scaffolds structure. The best structure of bio scaffolds was achieved with 0.4 mm nozzle diameter and 0.4 space between rows.

Mechanical and biological performance of printed alginate/methylcellulose/halloysite nanotube/polyvinylidene fluoride bio-scaffolds.

Use of artificial cartilage due to its poor regenerative characteristics is a challenging issue in the field of tissue engineering. In this regard, three-dimensional printing (3D) technique because of its perfect structural control is one of the best methods for producing biological scaffolds. Proper biomaterials for cartilage repairs with good mechanical and biological properties and the high ability for 3D printing are limited. In this paper, a novel biomaterial consisting of Alginate (AL), Methylcellulose (MC), Halloysite Nanotube (HNT), and Polyvinylidene Fluoride (PVDF) was printed and characterized for cartilage scaffold applications. Calcium chloride (CaCl2) was used as a crosslinker for biomaterial after printing. Scanning Electron Microscopy (SEM), Energy-Dispersive X-Ray Spectroscopy (EDX), X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), tensile and compressive tests, chondrocytes seeding, cells staining, and MTT assay were carried out in the present work. The results show that in constant concentrations of AL, MC, and PVDF (40 mg/ml AL, 30 mg/ml MC, and 1% PVDF) when concentration of HNT increased from 20 mg/ml (S2) to 40 mg/ml (S14) tensile strength increased from 164 up to 381 kPa and compressive stress increased from 426 up to 648 kPa. According to spectroscopy and calorimetry results, Biomaterial shows an amorphous structure with good miscibility and a high percentage of water in its structure. PVDF reduces mechanical properties by 7% while increases cell viability by 8.75%. Histological studies and MTT assay results showed a high improvement in the percentage of living cells at the first 4 days of cell cultivation.

An Experimental Study on the Mechanical and Biological Properties of Bio-Printed Alginate/Halloysite Nanotube/Methylcellulose/Russian Olive-Based Scaffolds.

Purpose: Cartilage shows neither repairs nor regenerative properties after trauma or gradual wear and causes severe pain due to bones rubbing. Bioprinting of tissue-engineered artificial cartilage is one of the most fast-growing sciences in this area that can help millions of people against this disease. Methods: Bioprinting of proper bioscaffolds for cartilage repair was the main goal of this study. The bioprinting process was achieved by a novel composition consisting of alginate (AL), Halloysite nanotube (HNT), and methylcellulose (MC) prepared in bio-ink. Also, the effect of Russian olive (RO) in chondrocytes growth on bioscaffolds was also investigated in this work. Compressive, hardness and viscosity tests, Energy-Dispersive X-Ray Spectroscopy (EDX), Fourier-Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), water-soluble Tetrazolium (WST) assay, and also transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were carried out. Results: The results show that in constant concentrations of AL, MC, and RO (20 mg/ml AL, 20 mg/ml MC, and 10 mg/ml RO) when concentration of HNT increased from 10 mg/ml (T-7) to 20 mg/ml (T-8) compressive stiffness increased from 241±45 kPa to 500.66±19.50 kPa. Also, 20 mg/ml of AL in composition saved proper water content for chondrocyte growth and produced good viscosity properties for a higher printing resolution. Conclusion: RO increased chondrocytes living cell efficiency by 11% on bioprinted scaffolds in comparison with the control group without RO. Results obtained through in-vivo studies were similar to those of in-vitro studies. According to the results, T-7 bio-ink has good potential in bioprinting of scaffolds in cartilage repairs.