Fabrication and characterization of a pro-angiogenic hydrogel derived from the human placenta.

Various hydrogels derived from the xenogeneic extracellular matrix (ECM) have been utilised to promote the repair and reconstruction of numerous tissues; however, there are few studies on hydrogels derived from allogeneic specimens. Human placenta derived hydrogels have been used in the therapy of ischaemic myocardium; however, their physicochemical properties and effects on cellular behaviour remain elusive. As the human placenta retains pro-angiogenic growth factors, it is hypothesized that the placenta hydrogels possess the potential to improve angiogenesis. In this study, a soluble decellularized human placenta matrix generated using a modified method could be stored in a powder form and could be used to form a hydrogel in vitro. Effective decellularization was evaluated by analysing the DNA content and histology images. The placenta hydrogel exhibited a fibrous porous morphology and was injectable. Fourier transform infrared (FTIR) spectroscopy revealed that the placenta hydrogel contained both collagen and sulfated glycosaminoglycans (GAGs). In addition, immunofluorescence imaging and enzyme-linked immunosorbent assay (ELISA) showed that the placenta hydrogel retained pro-angiogenic growth factors, including VEGF and bFGF, and transforming growth factor-ß1 (TGF-ß1). Further in vitro and in vivo analyses confirmed that the placenta hydrogel exerted better pro-angiogenic effects than a collagen type I hydrogel. Histological data also showed that the placenta hydrogels did not elicit a grave inflammatory response. In conclusion, the results suggest that placenta hydrogels may be deemed an attractive scaffold for regenerative medicine applications, especially in promoting vessel formation.

Association Between Genetic Polymorphisms of Metabolic Enzymes and Azathioprine-Induced Myelosuppression in 1,419 Chinese Patients: A Retrospective Study.

The aim of this study was to investigate the correlation between genetic polymorphisms of azathioprine-metabolizing enzymes and adverse reactions of myelosuppression. To this end, a retrospective analysis was performed on 1,419 Chinese patients involving 40 different diseases and 3 genes: ITPA (94C>A), TPMT*3 (T>C), and NUDT15 (415C>T). Strict inclusion and exclusion criteria were established to collect the relative cases, and the correlation between azathioprine and myelosuppression was evaluated by adverse drug reaction criteria. The mutation rates of the three genes were 29.32, 3.73, and 21.92% and grades I to IV myelosuppression occurred in 54 (9.28%) of the 582 patients who took azathioprine. The highest proportion of myelosuppression was observed in 5 of the 6 (83.33%) patients carrying the NUDT15 (415C>T) TT genotype and 12 of the 102 (11.76%) patients carrying the NUDT15 (415C>T) CT genotype. Only the NUDT15 (415C>T) polymorphism was found to be associated with the adverse effects of azathioprine-induced myelosuppression (odds ratio [OR], 51.818; 95% CI, 5.280-508.556; p = 0.001), which suggested that the NUDT15 (415C>T) polymorphism could be an influencing factor of azathioprine-induced myelosuppression in the Chinese population. Epistatic interactions between ITPA (94C>A) and NUDT15 (415C>T) affect the occurrence of myelosuppression. Thus, it is recommended that the genotype of NUDT15 (415C>T) and ITPA (94C>A) be checked before administration, and azathioprine should be avoided in patients carrying a homozygous NUDT15 (415C>T) mutation. This study is the first to investigate the association between genetic polymorphisms of these three azathioprine-metabolizing enzymes and myelosuppression in a large number of cases with a diverse range of diseases.

Production and Characterization of Composite Chitosan Hydrogel Containing Extracellular Matrix Particles for Tissue Engineering Applications.

Chitosan-based hydrogels have been extensively used for tissue regeneration due to the excellent biocompatibility and biodegradability. For lack of endogenous extracellular biomacromolecules, its application is obviously limited. Because of robust biological activity, porcine small intestinal submucosa (SIS) has been considered as promising candidates to increase the bioactivity of hydrogels. Herein, a facile method for the fabrication of SIS powders (SISP)/chitosan chloride (CSCl)-ß-glycerol phosphate (GP)-hydroxyethyl cellulose (HEC) hydrogel was developed. FTIR imaging results demonstrated that SISP and CSCl could be well mixed to form porous three-dimensional SISP/CSCl composite, which underwent sol-gel phage transition from solution to non-flowing hydrogel at 37 °C. Interestingly, the sustained release of VEGF and b-FGF within the composite hydrogel was determined and no initial burst release was observed. SISP/CSCl composite supported the survival and proliferation of NIH 3T3 cells in vitro and good biocompatibility in the SD rats subcutis up to 8 weeks. Furthermore, incorporated with SISP into CSCl delayed the degradation of SISP in vivo, as characterized by histological and High-Frequency Ultrasound (HFUS) measurement. Thus, all the findings suggested that the newlydeveloped injectable and thermosensitive SISP/CSCl composite was a promising and attractive candidate for soft tissue regeneration in the minimally-invasive way.

Preparation and characterization of pro-angiogenic gel derived from small intestinal submucosa.

Gels derived from decellularized small intestinal submucosa (SIS) have been used to repair ischemic myocardium and deliver protein drug. However, their material properties and effects on cell behavior are not well understood, in part because of the difficulty of gelling in vitro. In this study, soluble SIS matrix, which was easily handled and could effectively gel, was successfully prepared using a modified method. Fourier transform infrared spectroscopy confirmed that the SIS gel contained not only collagen but also sulfated glycosaminoglycans (sGAGs). Interestingly, the sustained release of vascular endothelial growth factor and basic fibroblast growth factor within the SIS gel was detected, and no initial burst release was observed. The SIS gel was more capable of evoking neovascularization than collagen type I gel, as determined by tube formation experiments in human umbilical vein endothelial cells, the mouse aortic ring assay, and animal experiments. The upregulated expression of kinase insert domain receptor (KDR), Notch1, and Ang2, the key genes in angiogenesis that were evaluated in HUVECs seeded on the SIS gel, confirmed that angiogenesis bioactive factors contained in the SIS gel are indeed active and effective. The SIS gel significantly promoted neovascularization compared to the collagen type I gel in vivo. Histology revealed adequate host tissue response in engraftment both types of gels. Together, these data demonstrate that the SIS gel is a promising and attractive candidate for tissue engineering, especially in promoting vessel formation. STATEMENT OF SIGNIFICANCE: The material properties of small intestinal submucosa (SIS) gel and the effect of these properties upon cell behavior are not well understood, in part due to the difficulty of gelling in vitro. In this study, soluble SIS matrix, which was easily handled and gelled was prepared using modified method. The material properties and biocompatibility of SIS gel were explored. The sustained release of growth factors from this gel was observed along with its degradation in vitro. The results demonstrate that the SIS gel promote angiogenesis in vitro and in vivo. The SIS gel biological properties suggest that the constituent ECM molecules released from the gel remain activity. These findings suggested that the SIS gel was a promising candidate for tissue engineering, especially in promoting vessel formation.