Effect of uncultured adipose-derived stromal vascular fraction on preventing urethral stricture formation in rats

Cell sheet formation enhances the therapeutic effects of adipose-derived stromal vascular fraction on urethral stricture

Urethral stricture (US) is a common disease in urology, lacking effective treatment options. Although injecting a stem cells suspension into the affected area has shown therapeutic benefits, challenges such as low retention rate and limited efficacy hinder the clinical application of stem cells. This study evaluates the therapeutic impact and the mechanism of adipose-derived vascular fraction (SVF) combined with cell sheet engineering technique on urethral fibrosis in a rat model of US. The results showed that SVF-cell sheets exhibit positive expression of α-SMA, CD31, CD34, Stro-1, and eNOS. In vivo study showed less collagen deposition, low urethral fibrosis, and minimal tissue alteration in the group receiving cell sheet transplantation. Furthermore, the formation of a three-dimensional (3D) tissue-like structure by the cell sheets enhances the paracrine effect of SVF, facilitates the infiltration of M2 macrophages, and suppresses the TGF-β/Smad2 pathway through HGF secretion, thereby exerting antifibrotic effects. Small animal in vivo imaging demonstrates improved retention of SVF cells at the damaged urethra site with cell sheet application. Our results suggest that SVF combined with cell sheet technology more efficiently inhibits the early stages of urethral fibrosis.

The Regenerative Microenvironment of the Tissue Engineering for Urethral Strictures

Urethral stricture caused by various reasons has threatened the quality of life of patients for decades. Traditional reconstruction methods, especially for long-segment injuries, have shown poor outcomes in treating urethral strictures. Tissue engineering for urethral regeneration is an emerging concept in which special designed scaffolds and seed cells are used to promote local urethral regeneration. The scaffolds, seed cells, various factors and the host interact with each other and form the regenerative microenvironment. Among the various interactions involved, vascularization and fibrosis are the most important biological processes during urethral regeneration. Mesenchymal stem cells and induced pluripotent stem cells play special roles in stricture repair and facilitate long-segment urethral regeneration, but they may also induce carcinogenesis and genomic instability during reconstruction. Nevertheless, current technologies, such as genetic engineering, molecular imaging, and exosome extraction, provide us with opportunities to manage seed cell-related regenerative risks. In this review, we described the interactions among seed cells, scaffolds, factors and the host within the regenerative microenvironment, which may help in determining the exact molecular mechanisms involved in urethral stricture regeneration and promoting clinical trials and the application of urethral tissue engineering in patients suffering from urethral stricture.

Negatively charged bladder acellular matrix loaded with positively charged adipose-derived mesenchymal stem cell-derived small extracellular vesicles for bladder tissue engineering

Adipose-derived mesenchymal stem cell-derived small extracellular vesicles (Ad-MSC-sEVs/AMEs) combined with scaffold materials are used in tissue-engineered bladders; however, the lack of retention leads to limited distribution of AMEs in the scaffold areas and low bioavailability of AMEs after bladder reconstruction. To improve retention of AMEs, we developed a novel strategy that modifies the surface charge of the bladder acellular matrix (BAM) via oxidative self-polymerization of dopamine-reducing graphene oxide (GO) and AMEs using ε-polylysine-polyethylene-distearyl phosphatidylethanolamine (PPD). We evaluated two BAM surface modification methods and evaluated the biocompatibility of materials and PPD and electrostatic adherence effects between PPD-modified AMEs and rGO-PDA/BAM in vivo and in vitro. Surface modification increased retention of AMEs, enhanced regeneration of bladder structures, and increased electrical conductivity of rGO-PDA/BAM, thereby improving bladder function recovery. RNA-sequencing revealed 543 miRNAs in human AMEs and 514 miRNAs in rat AMEs. A Venn diagram was used to show target genes of miRNA with the highest proportion predicted by the four databases; related biological processes and pathways were predicted by KEGG and GO analyses. We report a strategy for improving bioavailability of AMEs for bladder reconstruction and reveal that enriched miR-21-5p targets PIK3R1 and activates the PI3K/Akt pathway to promote cell proliferation and migration.

The Effect of Tissue Stromal Vascular Fraction as Compared to Cellular Stromal Vascular Fraction to Treat Anal Sphincter Incontinence

BACKGROUND

The long-term prognosis of current treatments for anal sphincter incontinence (ASI) is poor. Here, we explored the efficacy of tissue adipose stromal vascular fraction SVF (tSVF) on ASI and compared it to that of cellular SVF (cSVF). We then investigated possible mechanisms.

METHODS

Rat cSVF and tSVF were isolated and labeled with DIL. One day after modeling, three groups received phosphate-buffered saline (PBS), cSVF, tSVF, respectively. The control group received nil modeling nor any treatments. The effect was assessed by function test for anal pressure and electromyography, and staining for fiber content, proliferation and differentiation at day 5 and day 10.

RESULTS

cSVF injection resulted in faster healing than tSVF. The cSVF group showed significant improvement on anal pressure on day 10. For the electromyography test, cSVF showed significant improvement for the frequencies on day 10, and for the peak values on both time points, while tSVF showed significant improvement for the peak values on day 10. The two SVF both alleviated fibrosis. Immunofluorescence tracing identified differentiation of some injected cells towards myosatellite cells and smooth muscle cells in both SVF groups. For all the tests, the tSVF group tends to have similar or lower effects than the cSVF group with no significant difference.

CONCLUSION

cSVF and tSVF are both safe and effective in treating ASI, while the effect of cSVF is slighter higher than tSVF.