Novel perfusion-decellularized method to prepare decellularized ureters for ureteral tissue-engineered repair

Biomedical Application of Decellularized Scaffolds

Tissue loss and end-stage organ failure are serious health problems across the world. Natural and synthetic polymer scaffold material based artificial organs play an important role in the field of tissue engineering and organ regeneration, but they are not from the body and may cause side effects such as rejection. In recent years, the biomimetic decellularized scaffold based materials have drawn great attention in the tissue engineering field for their good biocompatibility, easy modification, and excellent organism adaptability. Therefore, in this review, we comprehensively summarize the application of decellularized scaffolds in tissue engineering and biomedicine in recent years. The preparation methods, modification strategies, construction of artificial tissues, and application in biomedical applications are discussed. We hope that this review will provide a useful reference for research on decellularized scaffolds and promote their application tissue engineering.

Bladder Acellular Matrix Prepared by a Self-Designed Perfusion System and Adipose-Derived Stem Cells to Promote Bladder Tissue Regeneration

The bladder patch constructed with the bladder acellular matrix (BAM) and adipose-derived stem cells (ASCs) was incubated with the omentum for bladder reconstruction in a rat model of bladder augmentation cystoplasty. A self-designed perfusion system and five different decellularization protocols were used to prepare the BAM. Finally, an optimal protocol (group C) was screened out by comparing the cell nucleus residue, collagen structure preservation and biologically active components retention of the prepared BAM. ASCs-seeded (BAM-ASCs group) and unseeded BAM (BAM group) were incubated with the omentum for 7 days to promote neovascularization and then perform bladder reconstruction. Hematoxylin and eosin and Masson’s trichrome staining indicated that the bladder patches in the BAM-ASCs group could better regenerate the bladder wall structure compared to the BAM group. Moreover, immunofluorescence analyses demonstrated that the ASCs could promote the regeneration of smooth muscle, neurons and blood vessels, and the physiological function (maximal bladder capacity, max pressure prior to voiding and bladder compliance) restoration in the BAM-ASCs group. The results demonstrated that the self-designed perfusion system could quickly and efficiently prepare the whole bladder scaffold and confirmed that the prepared BAM could be used as the scaffold material for functional bladder tissue engineering applications.

Renal engineering: strategies to address the problem of the ureter

Current techniques for making renal organoids generate tissues that show function when transplanted into a host, but they have no ureter through which urine can drain. There are at least 4 possible strategies for adding a ureter: connecting to ta host ureter; inducing an engineered kidney to make a ureter; making a stem-cell derived ureter; and replacement of only damaged cortex and outer medulla, using remaining host calyces, pelvis and ureter. Here we review progress: local BMP4 can induce a collecting duct tubule to become a ureter; a urothelial tube can be produced directly from pluripotent cells, and connect to the collecting duct system of a renal organoid; it is possible to graft ES cell-derived ureters into host kidney rudiments and see connection, smooth muscle development and spontaneous contraction, but this has not yet been achieved with all components being derived from ES cells. Remaining problems are discussed.

Bi-layer silk fibroin skeleton and bladder acellular matrix hydrogel encapsulating adipose-derived stem cells for bladder reconstruction

A scaffold, constructed from a bi-layer silk fibroin skeleton (BSFS) and a bladder acellular matrix hydrogel (BAMH) encapsulated with adipose-derived stem cells (ASCs), was developed for bladder augmentation in a rat model. The BSFS, prepared from silk fibroin (SF), had good mechanical properties that allowed it to maintain the scaffold shape and be used for stitching. The prepared BAM was digested by pepsin and the pH was adjusted to harvest the BAMH that provided an extracellular environment for the ASCs. The constructed BSFS-BAMH-ASCs and BSFS-BAMH scaffolds were wrapped in the omentum to promote neovascularization and then used for bladder augmentation; at the same time, a cystotomy was used as the condition for the control group. Histological staining and immunohistochemical analysis confirmed that the omentum incubation could promote scaffold vascularization. Hematoxylin and eosin and Masson's trichrome staining indicated that the BSFS-BAMH-ASCs scaffold regenerated the bladder wall structure. In addition, immunofluorescence analyses confirmed that the ASCs could promote the regeneration of smooth muscle, neurons and blood vessels and the restoration of physiological function. These results demonstrated that the BSFS-BAMH-ASCs may be a promising scaffold for promoting bladder wall regeneration and the restoration of physiological function of the bladder in a rat bladder augmentation model.

A Preliminary Study on the Promotion of Canine Adipose-Derived Stem Cell Differentiation by Perfusion-Decellularized Ureter Matrix

BACKGROUND

This study was to assess the possibility of the perfusing decellularized ureters (DUs) promoting the differentiation of the canine adipose stem cell (cASCs).

METHODS

cASCs were isolated and cultured in different induction media to determine their multidirectional differentiation potential. The perfusion system was used to prepare the DUs, and the prepared DUs were systematically evaluated. The DU coating was prepared by enzymatic digestion for cell culture. The cASCs were seeded on the coverslips covered with DU coating and samples were collected on days 3, 7, and 10. Immunofluorescence staining and molecular biology testing were used to examine the differentiation of cASCs seeded on the DU coating.

RESULTS

The cASCs were isolated and identified by flow cytometry. The prepared DUs removed the nuclear materials, and the 3-dimensional structure and biological compositions of the ureter were well preserved. Immunofluorescence staining showed the expression of anti-alpha smooth muscle actin (α-SMA). Western blot results suggested that the content of α-SMA in the experimental group was significantly higher than that in the control group at 3 different time points, and the mRNA expressions of α-SMA in the experimental group gradually increased with extended the culture time, whereas there was no significant change in the control group.

CONCLUSION

The cASCs seeded on the coverslips of DU coating could differentiate into smooth muscle cells, and the number of differentiated cASCs increased significantly with extended incubation time.

Regeneration of muscular wall of the bladder using a ureter matrix graft as a scaffold

We investigated a method for bladder augmentation in rats using a decellularized ureter graft. We used 16 rats divided into two groups of eight. After partial cystectomy, the bladders in group 1 were grafted with a 1 cm² patch of human decellularized ureter. Rats in group 2 were untreated controls. Biopsies of the graft were taken at 1, 3 and 9 months postoperatively for histological investigation. Total removal of cells and preservation of extracellular matrix (ECM) was confirmed in the decellularized ureter. Histological examination after 1 month revealed few cells at the border of the graft. Three months after the operation, the graft was infiltrated by vessels and smooth muscle and the mucosal lining was complete. All bladder wall components resembled native bladder wall by 9 months after implantation. CD34, CD31, α-smooth muscle actin, S100, cytokeratin AE1/AE3 and vimentin were detected 9 months after the operation. We demonstrated the potential of decellularized biocompatible ureteric grafts for use as a natural collagen scaffold for bladder repair in rats.