Evaluating the biodegradability of Gelatin/Siloxane/Hydroxyapatite (GS-Hyd) complex in vivo and its ability for adhesion and proliferation of rat bone marrow mesenchymal stem cells

Comparing bone tissue engineering efficacy of HDPSCs, HBMSCs on 3D biomimetic ABM-P-15 scaffolds in vitro and in vivo

Human bone marrow mesenchymal stem cells (HBMSCs) has been the gold standard for bone regeneration. However, the low proliferation rate and long doubling time limited its clinical applications. This study aims to compare the bone tissue engineering efficacy of human dental pulp stem cells (HDPSCs) with HBMSCs in 2D, and 3D anorganic bone mineral (ABM) coated with a biomimetic collagen peptide (ABM-P-15) for improving bone-forming speed and efficacy in vitro and in vivo. The multipotential of both HDPSCs and HBMSCs have been compared in vitro. The bone formation of HDPSCs on ABM-P-15 was tested using in vivo model. The osteogenic potential of the cells was confirmed by alkaline phosphatase (ALP) and immunohistological staining for osteogenic markers. Enhanced ALP, collagen, lipid droplet, or glycosaminoglycans production were visible in HDPSCs and HBMSCs after osteogenic, adipogenic and chondrogenic induction. HDPSC showed stronger ALP staining compared to HBMSCs. Confocal images showed more viable HDPSCs on both ABM-P-15 and ABM scaffolds compared to HBMSCs on similar scaffolds. ABM-P-15 enhanced cell attachment/spreading/bridging formation on ABM-P-15 scaffolds and significantly increased quantitative ALP specific activities of the HDPSCs and HBMSCs. After 8 weeks in vivo implantation in diffusion chamber model, the HDPSCs on ABM-P-15 scaffolds showed extensive high organised collagenous matrix formation that was positive for COL-I and OCN compared to ABM alone. In conclusion, the HDPSCs have a higher proliferation rate and better osteogenic capacity, which indicated the potential of combining HDPSCs with ABM-P-15 scaffolds for improving bone regeneration speed and efficacy.

Microwave-induced rapid formation of biomimetic hydroxyapatite coating on gelatin-siloxane hybrid microspheres in 10X-SBF solution

Bioactive materials can attract calcium and phosphate ions in simulated body fluid (SBF) solution to mimic the composition of extracellular matrix (ECM). Rapid biodegradation rate of natural polymers in contact with water-based solutions and time-consuming process of mineralization in SBF led to using concentrated simulated media. Herein, gelatin-siloxane microspheres were fabricated via single emulsion method. Then hybrid spheres were immersed in the modified 10X-SBF solution, and microwave energy (600 W) was expanded for the rapid formation of hydroxyapatite (HA) on the spheres. Results indicated homogeneous coating of microspheres and high similarity of synthesized HA to the bone composition. Increasing intensity of HA-related peaks in Fourier transform infrared spectrum, X-ray diffraction and surface roughness after utilizing microwave-assisted method confirmed high efficiency of this technique in biomimetic mineralization of structures. Cell culture studies with human osteosarcoma cell lines (MG-63) demonstrated that mineralized HA in 10X-SBF solution under microwave treatment could be able to mimic bone ECM for tissue regeneration applications in the shortest time and highest similarity to the natural tissue.

A comparison study on the behavior of human endometrial stem cell-derived osteoblast cells on PLGA/HA nanocomposite scaffolds fabricated by electrospinning and freeze-drying methods

Background

An engineered tissue structure is an artificial scaffold combined with cells and signaling factors. Among various polymers, the polylactide-co-glycolide/hydroxyapatite (PLGA/HA) has attracted much attention due to their optimal properties. The aim of this study was to study the behavior of human endometrial stem cell (hEnSC)-derived osteoblast cells cultured on PLGA/HA nanocomposite scaffolds.

Methods

hEnSCs were isolated and exposed to osteogenic media for 21 days. Differentiated cells were cultured on PLGA/HA synthetic scaffolds. The PLGA/HA-based nanocomposite scaffolds were fabricated using either electrospinning or freeze-drying methods. Behavior of the cells was evaluated a week after seeding hEnSC-derived osteoblast-like cells on these scaffolds. Osteogenesis was investigated in terms of alkaline phosphatase activity, gene expression, immunocytochemistry (ICC), proliferation, and scanning electron microscopy (SEM). Moreover, scaffold properties, such as pore size and morphology of the cells, onto the scaffolds were evaluated using SEM. Furthermore, biocompatibility of these scaffolds was confirmed by 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

Results

The matrix mineralization was proved by alizarin red staining, and the osteogenic media-treated cultures positively expressed osteocalcin and osteopontin markers. Moreover, qRT-PCR results confirmed the positive gene expression of osteopontin and osteonectin in the differentiated osteoblast-like cells. The results of behavior assessment of the cultured cells on electrospinning and freeze-dried scaffolds showed that the behavior of the cultured cells on the freeze-dried PLGA/HA scaffolds was significantly better than the electrospinning PLGA/HA scaffolds.

Conclusion

It has been shown that the freeze-dried PLGA/HA nanocomposite scaffolds can appropriately support the attachment and proliferation of the differentiated osteoblast cells and are a suitable candidate for bone tissue engineering.

Differential degradation rate and underlying mechanism of a collagen/chitosan complex in subcutis, spinal cord and brain tissues of rat

Degradation rate is an important index for evaluating biomaterials. The authors' aim was to determine whether the degradation rate of biomaterials is different in distinct tissues and to clarify the underlying mechanism of degradation. The collagen-chitosan (CG-CS) composite scaffolds were prepared using freeze-drying technology. The porosity, water absorption and swelling ratio of the scaffolds were tested in vitro. The scaffolds were implanted into the subcutis, spinal cord and brain tissues of SD rats, the rate of degradation was assessed by continuous monitoring of weight loss, the pathological changes of target areas were observed by histological staining, and matrix metalloproteinase 9 (MMP-9) and lysozyme were detected at the rapid stage of degradation of the scaffolds. Physical and chemical property testing confirmed that CG-CS composite scaffold components can meet the biological requirements of in vivo transplantation. The in vivo experimental results showed that the scaffolds were completely absorbed in the subcutis at 12 days, the scaffolds in the spinal cord and brain groups exhibited progressive mass loss starting from the 3rd week, and a substantial fraction of the scaffold was degraded at 12 weeks. HE staining found that compared with the spinal cord and brain groups, macrophages and capillaries appeared earlier in the subcutis group, and the number was significantly higher (P < 0.05). Western blot analysis showed that the MMP-9 and lysozyme levels in the subcutis were higher than those in the spinal cord and brain (P < 0.05). The results of in vivo experiments demonstrated that the CG-CS scaffold has good biocompatibility and biodegradability, while the rate of degradation was significantly different between the three tissues at the same time point. Macrophage behavior and vascularization in different parts of the body may result in control over the balance of degradation and reconstruction.

A unique heterologous fibrin sealant (HFS) as a candidate biological scaffold for mesenchymal stem cells in osteoporotic rats

Background

The injection of mesenchymal stem cells (MSCs) directly into the bone of osteoporotic (OP) patients for rapid recovery has been studied worldwide. Scaffolds associated with MSCs are used to maintain and avoid cell loss after application. A unique heterologous fibrin sealant (HFS) derived from snake venom was evaluated for the cytotoxicity of its main components and as a three-dimensional biological scaffold for MSCs to repair a critical femur defect in osteoporotic rats.

Methods

The cytotoxicity of HFS was assessed using a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazoliumbromide (MTT) assay and transmission electron microscopy. The cells were cultured, characterized by flow cytometry and differentiated into the osteogenic lineage. Two-month-old rats underwent ovariectomy to induce OP. After 3 months, a 5 mm critical bone defect was made in the distal end of the rat femurs and filled with HFS; HFS + MSCs; and HFS + MSCs D (differentiated into the osteogenic lineage) to evaluate the effects. An injury control group (injury and no treatment) and blank control group (no injury and no treatment) were also included. The animals were observed at days 14 and 28 by microtomographic (micro-CT) analyses, histologic and biochemical analysis, as well as scanning electron microscopy.

Results

The results revealed that one of the compounds of HFS, the thrombin-like enzyme extracted from snake venom, had no cytotoxic effects on the MSCs. OP was successfully induced, as demonstrated by the significant differences in the levels of 17β-estradiol, Micro-CT analyses and alkaline phosphatase between the ovariectomized (OVX) and non-ovariectomized (NOVX) groups. The histological data revealed that at 14 days after surgery in both the OVX and NOVX animals, the HFS + CTMs and HFS + CTMsD showed a higher formation of bone cells at the site in relation to the control group (without treatment). Collagen formation was evidenced through bone neoformation in all treated and control groups. No morphological differences in the femurs of the NOVX and OVX animals were observed after the surgical procedure. Scanning electron microscopy (SEM) confirmed the histological analysis.

Conclusions

The new HFS composed of two non-toxic components for MSCs showed capacity to promote the recovery of the bone lesions in OVX and NOVX animals at 14 days after surgery. In addition, the HFS enabled the differentiation of MSCs into MSCs D in the group treated with HFS + MSCs. Using the MSCs and/or MSCs D together with this biopharmaceutical could potentially enable significant advances in the treatment of osteoporotic fractures. Future clinical trials will be necessary to confirm these results.

Osteogenic Differentiation of Bone Marrow Stem Cell in Poly(Lactic-co-Glycolic Acid) Scaffold Loaded Various Ratio of Hydroxyapatite

BACKGROUND AND OBJECTIVES

Hydroxyapatite has biocompatibility and bioactivity and similar to bone of in human body. The purpose of this study is to evaluate osteogenic differentiation of bone marrow stem cell (BMSC) in PLGA Scaffold added various ratio of hydroxyapatite (HAp).

METHODS AND RESULTS

PLGA and PLGA/HAp scaffold were prepared using solvent casting/salt-leaching method. BMSC was seeded on the PLGA and PLGA/HAp scaffold and the samples were cultured in 37℃ incubator with 5% CO2 for 28 days. Alkaline phosphatase (ALP) was carried out to evaluate alkaline phosphatase activity at 1, 3, 7, 10 and 14 days. Alizarin Red S stating was performed to identify calcium in scaffold at 1, 7, 14, 21 and 28 days. Compressive strength was measured to evaluate mechanical property of scaffold. To confirm cell viability, MTT was carried out at 1, 3, 7, 14 and 28 days. RT-PCR was performed to verify specific marker expression of osteoblast and stem cell at 7, 14, 21 and 28 days.

CONCLUSIONS

Osteogenic differentiation of BMSC was confirmed through ALP, RT-PCR, and alizarin red S staining in this study. These results suggest that HAp helps osteogenic differentiation of BMSC.

Engineering ear-shaped cartilage using electrospun fibrous membranes of gelatin/polycaprolactone

Tissue engineering approach continuously requires for emerging strategies to improve the efficacy in repairing and regeneration of tissue defects. Previously, we developed a sandwich model strategy for cartilage engineering, using the combination of acellular cartilage sheets (ACSs) and chondrocytes. However, the process for the preparation of ACSs is complicated, and it is also difficult to obtain large ACSs. The aim of this study was to engineer cartilage with precise three-dimensional (3-D) structures by applying electrospun fibrous membranes of gelatin/polycaprolactone (GT/PCL). We first prepared the electrospun GT/PCL membranes into rounded shape, and then seeded chondrocytes in the sandwich model. After in vitro and in vivo cultivation, the newly formed cartilage-like tissues were harvested. Macroscopic observations and histological analysis confirmed that the engineering of cartilage using the electrospun GT/PCL membranes was feasible. An ear-shaped cartilage was then constructed in the sandwich model, with the help of an ear-shaped titanium alloy mold. After 2 weeks of culture in vitro and 6 weeks of subcutaneous incubation in vivo, the ear-shaped cartilage largely maintained their original shape, with a shape similarity up to 91.41% of the titanium mold. In addition, the engineered cartilage showed good elasticity and impressive mechanical strength. These results demonstrated that the engineering of 3-D cartilage in a sandwich model using electrospun fibrous membranes was a facile and effective approach, which has the potential to be applied for the engineering of other tissues with complicated 3-D structures.