A nonhuman primate model for urinary bladder regeneration using autologous sources of bone marrow-derived mesenchymal stem cells

Proteomic profiling of regenerated urinary bladder tissue in a non-human primate augmentation model

Urinary bladder dysfunction can be caused by environmental, genetic, and developmental insults. Depending upon insult severity, the bladder may lose its ability to maintain volumetric capacity and intravesical pressure resulting in renal deterioration. Bladder augmentation enterocystoplasty (BAE) is utilized to increase bladder capacity to preserve renal function using autologous bowel tissue as a "patch." To avoid the clinical complications associated with this procedure, we have engineered composite grafts comprised of autologous bone marrow mesenchymal stem cells (MSCs) co-seeded with CD34+ hematopoietic stem/progenitor cells (HSPCs) onto a pliable synthetic scaffold [poly(1,8-octamethylene-citrate-co-octanol)(POCO)] or a biological scaffold (SIS; small intestinal submucosa) to regenerate bladder tissue in our baboon bladder augmentation model. We set out to determine the global protein expression profile of bladder tissue that has undergone regeneration with the aforementioned stem cell seeded scaffolds along with baboons that underwent BAE. Data demonstrate that POCO and SIS grafted animals share high protein homogeneity between native and regenerated tissues while BAE animals displayed heterogeneous protein expression between the tissues following long-term engraftment. We posit that stem cell-seeded scaffolds can recapitulate tissue that is nearly indistinguishable from native tissue at the protein level and may be used in lieu of procedures such as BAE.

Expansion of human umbilical cord derived mesenchymal stem cells in regenerative medicine

BACKGROUND

Stem cells are undifferentiated cells that possess the potential for self-renewal with the capacity to differentiate into multiple lineages. In humans, their limited numbers pose a challenge in fulfilling the necessary demands for the regeneration and repair of damaged tissues or organs. Studies suggested that mesenchymal stem cells (MSCs), necessary for repair and regeneration via transplantation, require doses ranging from 10 to 400 million cells. Furthermore, the limited expansion of MSCs restricts their therapeutic application.

AIM

To optimize a novel protocol to achieve qualitative and quantitative expansion of MSCs to reach the targeted number of cells for cellular transplantation and minimize the limitations in stem cell therapy protocols.

METHODS

Human umbilical cord (hUC) tissue derived MSCs were obtained and re-cultured. These cultured cells were subjected to the following evaluation procedures: Immunophenotyping, immunocytochemical staining, trilineage differentiation, population doubling time and number, gene expression markers for proliferation, cell cycle progression, senescence-associated β-galactosidase assay, human telomerase reverse transcriptase (hTERT) expression, mycoplasma, cytomegalovirus and endotoxin detection.

RESULTS

Analysis of pluripotent gene markers Oct4, Sox2, and Nanog in recultured hUC-MSC revealed no significant differences. The immunophenotypic markers CD90, CD73, CD105, CD44, vimentin, CD29, Stro-1, and Lin28 were positively expressed by these recultured expanded MSCs, and were found negative for CD34, CD11b, CD19, CD45, and HLA-DR. The recultured hUC-MSC population continued to expand through passage 15. Proliferative gene expression of Pax6, BMP2, and TGFb1 showed no significant variation between recultured hUC-MSC groups. Nevertheless, a significant increase (P < 0.001) in the mitotic phase of the cell cycle was observed in recultured hUC-MSCs. Cellular senescence markers (hTERT expression and β-galactosidase activity) did not show any negative effect on recultured hUC-MSCs. Additionally, quality control assessments consistently confirmed the absence of mycoplasma, cytomegalovirus, and endotoxin contamination.

CONCLUSION

This study proposes the development of a novel protocol for efficiently expanding stem cell population. This would address the growing demand for larger stem cell doses needed for cellular transplantation and will significantly improve the feasibility of stem cell based therapies.

A wireless, implantable bioelectronic system for monitoring urinary bladder function following surgical recovery

Partial cystectomy procedures for urinary bladder-related dysfunction involve long recovery periods, during which urodynamic studies (UDS) intermittently assess lower urinary tract function. However, UDS are not patient-friendly, they exhibit user-to-user variability, and they amount to snapshots in time, limiting the ability to collect continuous, longitudinal data. These procedures also pose the risk of catheter-associated urinary tract infections, which can progress to ascending pyelonephritis due to prolonged lower tract manipulation in high-risk patients. Here, we introduce a fully bladder-implantable platform that allows for continuous, real-time measurements of changes in mechanical strain associated with bladder filling and emptying via wireless telemetry, including a wireless bioresorbable strain gauge validated in a benchtop partial cystectomy model. We demonstrate that this system can reproducibly measure real-time changes in a rodent model up to 30 d postimplantation with minimal foreign body response. Studies in a nonhuman primate partial cystectomy model demonstrate concordance of pressure measurements up to 8 wk compared with traditional UDS. These results suggest that our system can be used as a suitable alternative to UDS for long-term postoperative bladder recovery monitoring.

Bibliometric analysis of organoids in regenerative medicine-related research worldwide over two decades (2002-2022)

Aim: This study aimed to evaluate the trends in organoid culture research within the field of regenerative medicine from 2002 to 2022. Methods: The worldwide distribution of organoid research in regenerative medicine articles indexed in the Scopus database was analyzed. Result: A total of 840 documents were analyzed, averaging 42 publications annually. The USA (n = 296) led in publications, followed by China (n = 127), Japan (n = 91) and the UK (n = 75). Since 2011, research has surged, particularly in China, which emerged as a prominent center. Conclusion: The findings highlight significant growth in organoid research, promising future organ transplantation. Research trends integrate tissue engineering, gene modification and induced pluripotent stem cell technologies, reflecting a move toward personalized medicine.

Multipotent bone marrow cell-seeded polymeric composites drive long-term, definitive urinary bladder tissue regeneration

To date, there are no efficacious translational solutions for end-stage urinary bladder dysfunction. Current surgical strategies, including urinary diversion and bladder augmentation enterocystoplasty (BAE), utilize autologous intestinal segments (e.g. ileum) to increase bladder capacity to protect renal function. Considered the standard of care, BAE is fraught with numerous short- and long-term clinical complications. Previous clinical trials employing tissue engineering approaches for bladder tissue regeneration have also been unable to translate bench-top findings into clinical practice. Major obstacles still persist that need to be overcome in order to advance tissue-engineered products into the clinical arena. These include scaffold/bladder incongruencies, the acquisition and utility of appropriate cells for anatomic and physiologic tissue recapitulation, and the choice of an appropriate animal model for testing. In this study, we demonstrate that the elastomeric, bladder biomechanocompatible poly(1,8-octamethylene-citrate-co-octanol) (PRS; synthetic) scaffold coseeded with autologous bone marrow-derived mesenchymal stem cells and CD34+ hematopoietic stem/progenitor cells support robust long-term, functional bladder tissue regeneration within the context of a clinically relevant baboon bladder augmentation model simulating bladder trauma. Partially cystectomized baboons were independently augmented with either autologous ileum or stem-cell-seeded small-intestinal submucosa (SIS; a commercially available biological scaffold) or PRS grafts. Stem-cell synergism promoted functional trilayer bladder tissue regeneration, including whole-graft neurovascularization, in both cell-seeded grafts. However, PRS-augmented animals demonstrated fewer clinical complications and more advantageous tissue characterization metrics compared to ileum and SIS-augmented animals. Two-year study data demonstrate that PRS/stem-cell-seeded grafts drive bladder tissue regeneration and are a suitable alternative to BAE.

Porous gelatin microspheres implanted with adipose mesenchymal stromal cells promote angiogenesis via protein kinase B/endothelial nitric oxide synthase signaling pathway in bladder reconstruction

BACKGROUND AIMS

Cell failure and angiogenesis are the key to bladder wall regeneration. Three-dimensional (3D) culture using porous gelatin microspheres (GMs) as a vehicle promotes stem cell proliferation and improves the paracrine capacity of cells. This study aimed to evaluate the therapeutic potential of GMs constructed from adipose-derived mesenchymal stromal cells (ADSCs) (ADSC-GMs) combined with bladder acellular matrix (BAM) in tissue-engineered bladders.

METHODS

Isolation of ADSCs, flow cytometry, scanning electron microscopy and cell counting kit-8, β-galactosidase and enzyme-linked immunosorbent assays were performed in vitro to compare two-dimensional (2D) and 3D cultures. In the in vivo study, male Sprague-Dawley rats were randomly divided into three groups: the BAM replacement alone (BAM) group, ADSCs grown on BAM in replacement (ADSC) group and ADSC-GMs combined with BAM followed by replacement (ADSC-GM) group. Bladder function assessed by urodynamics after 12 weeks of bladder replacement, and the rats were sacrificed at 4 and 12 weeks for further experiments.

RESULTS

The in vitro results showed that GM culture promoted ADSC proliferation, inhibited apoptosis and delayed senescence compared with those in the 2D culture. In addition, ADSC-GMs increased the secretion of the angiogenic factors vascular endothelial growth factor, platelet-derived growth factor-BB, and basal fibroblast growth factor. In vivo experiments revealed that ADSC-GMs adhered to the BAM for longer than ADSCs. Moreover, ADSC-GMs significantly promoted the regeneration of bladder vessels and smooth muscle, thereby facilitating the recovery of bladder function. The expression of phosphorylated protein kinase B (AKT) and phosphorylated endothelial nitric oxide synthase (eNOS) was significantly greater in the ADSC-GMs group compared with the BAM and ADSCs groups.

CONCLUSIONS

ADSC-GMs increased retention of ADSCs on the BAM, thereby promoting the regeneration and functional recovery of the bladder tissue. ADSC-GMs promoted angiogenesis by activating the AKT/eNOS pathway.

Proteomic profiling of regenerated urinary bladder tissue with stem cell seeded scaffold composites in a non-human primate bladder augmentation model

Urinary bladder insult can be caused by environmental, genetic, and developmental factors. Depending upon insult severity, the bladder may lose its ability to maintain capacity and intravesical pressures resulting in renal deterioration. Bladder augmentation enterocystoplasty (BAE) is employed to increase bladder capacity to preserve renal function using autologous bowel tissue as a "patch." To avoid the clinical complications associated with this procedure, we have engineered composite grafts comprised of autologous bone marrow mesenchymal stem cells (MSCs) with CD34+ hematopoietic stem/progenitor cells (HSPCs) co-seeded onto a pliable synthetic scaffold [POCO; poly(1,8-octamethylene-citrate-co-octanol)] or a biological scaffold (SIS; small intestinal submucosa) to regenerate bladder tissue in a baboon bladder augmentation model. We set out to determine the protein expression profile of bladder tissue that has undergone regeneration with the aforementioned stem cell seeded scaffolds along with baboons that underwent BAE. Data demonstrate that POCO and SIS grafted animals share high protein homogeneity between native and regenerated tissues while BAE animals displayed heterogenous protein expression between the tissues following long-term engraftment. We posit that stem cell seeded scaffolds can recapitulate tissue that is almost indistinguishable from native tissue at the protein level and may be used in lieu of procedures such as BAE.

Tissue Engineering Neovagina for Vaginoplasty in Mayer-Rokitansky-Küster-Hauser Syndrome and Gender Dysphoria Patients: A Systematic Review

Background: Vaginoplasty is a surgical solution to multiple disorders, including Mayer-Rokitansky-Küster-Hauser syndrome and male-to-female gender dysphoria. Using nonvaginal tissues for these reconstructions is associated with many complications, and autologous vaginal tissue may not be sufficient. The potential of tissue engineering for vaginoplasty was studied through a systematic bibliography search. Cell types, biomaterials, and signaling factors were analyzed by investigating advantages, disadvantages, complications, and research quantity. Search Methods: A systematic search was performed in Medline, EMBASE, Web of Science, and Scopus until March 8, 2022. Term combinations for tissue engineering, guided tissue regeneration, regenerative medicine, and tissue scaffold were applied, together with vaginoplasty and neovagina. The snowball method was performed on references and a Google Scholar search on the first 200 hits. Original research articles on human and/or animal subjects that met the inclusion (reconstruction of vaginal tissue and tissue engineering method) and no exclusion criteria (not available as full text; written in foreign language; nonoriginal study article; genital surgery other than neovaginal reconstruction; and vaginal reconstruction with autologous or allogenic tissue without tissue engineering or scaffold) were assessed. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist, the Newcastle-Ottawa Scale, and the Gold Standard Publication Checklist were used to evaluate article quality and bias. Outcomes: A total of 31 out of 1569 articles were included. Data extraction was based on cell origin and type, biomaterial nature and composition, host species, number of hosts and controls, neovaginal size, replacement fraction, and signaling factors. An overview of used tissue engineering methods for neovaginal formation was created, showing high variance of cell types, biomaterials, and signaling factors and the same topics were rarely covered multiple times. Autologous vaginal cells and extracellular matrix-based biomaterials showed preferential properties, and stem cells carry potential. However, quality confirmation of orthotopic cell-seeded acellular vaginal matrix by clinical trials is needed as well as exploration of signaling factors for vaginoplasty. Impact statement General article quality was weak to sufficient due to unreported cofounders and incomplete animal study descriptions. Article quality and heterogenicity made identification of optimal cell types, biomaterials, or signaling factors unreliable. However, trends showed that autologous cells prevent complications and compatibility issues such as healthy cell destruction, whereas stem cells prevent cross talk (interference of signaling pathways by signals from other cell types) and rejection (but need confirmation testing beyond animal trials). Natural (orthotopic) extracellular matrix biomaterials have great preferential properties that encourage future research, and signaling factors for vascularization are important for tissue engineering of full-sized neovagina.

Tissue Engineering and Regenerative Medicine in Pediatric Urology: Urethral and Urinary Bladder Reconstruction

In the case of pediatric urology there are several congenital conditions, such as hypospadias and neurogenic bladder, which affect, respectively, the urethra and the urinary bladder. In fact, the gold standard consists of a urethroplasty procedure in the case of urethral malformations and enterocystoplasty in the case of urinary bladder disorders. However, both surgical procedures are associated with severe complications, such as fistulas, urethral strictures, and dehiscence of the repair or recurrence of chordee in the case of urethroplasty, and metabolic disturbances, stone formation, urine leakage, and chronic infections in the case of enterocystoplasty. With the aim of overcoming the issue related to the lack of sufficient and appropriate autologous tissue, increasing attention has been focused on tissue engineering. In this review, both the urethral and the urinary bladder reconstruction strategies were summarized, focusing on pediatric applications and evaluating all the biomaterials tested in both animal models and patients. Particular attention was paid to the capability for tissue regeneration in dependence on the eventual presence of seeded cell and growth factor combinations in several types of scaffolds. Moreover, the main critical features needed for urinary tissue engineering have been highlighted and specifically focused on for pediatric application.

Porcine Small Intestinal Submucosa (SIS) as a Suitable Scaffold for the Creation of a Tissue-Engineered Urinary Conduit: Decellularization, Biomechanical and Biocompatibility Characterization Using New Approaches

Bladder cancer (BC) is among the most common malignancies in the world and a relevant cause of cancer mortality. BC is one of the most frequent causes for bladder removal through radical cystectomy, the gold-standard treatment for localized muscle-invasive and some cases of high-risk, non-muscle-invasive bladder cancer. In order to restore urinary functionality, an autologous intestinal segment has to be used to create a urinary diversion. However, several complications are associated with bowel-tract removal, affecting patients' quality of life. The present study project aims to develop a bio-engineered material to simplify this surgical procedure, avoiding related surgical complications and improving patients' quality of life. The main novelty of such a therapeutic approach is the decellularization of a porcine small intestinal submucosa (SIS) conduit to replace the autologous intestinal segment currently used as urinary diversion after radical cystectomy, while avoiding an immune rejection. Here, we performed a preliminary evaluation of this acellular product by developing a novel decellularization process based on an environmentally friendly, mild detergent, i.e., Tergitol, to replace the recently declared toxic Triton X-100. Treatment efficacy was evaluated through histology, DNA, hydroxyproline and elastin quantification, mechanical and insufflation tests, two-photon microscopy, FTIR analysis, and cytocompatibility tests. The optimized decellularization protocol is effective in removing cells, including DNA content, from the porcine SIS, while preserving the integrity of the extracellular matrix despite an increase in stiffness. An effective sterilization protocol was found, and cytocompatibility of treated SIS was demonstrated from day 1 to day 7, during which human fibroblasts were able to increase in number and strongly organize along tissue fibres. Taken together, this in vitro study suggests that SIS is a suitable candidate for use in urinary diversions in place of autologous intestinal segments, considering the optimal results of decellularization and cell proliferation. Further efforts should be undertaken in order to improve SIS conduit patency and impermeability to realize a future viable substitute.

Application of biomaterials and tissue engineering in bladder regeneration

The primary functions of the bladder are storing urine under low and stable pressure and micturition. Various forms of trauma, tumors, and iatrogenic injuries can cause the loss of or reduce bladder function or capacity. If such damage is not treated in time, it will eventually lead to kidney damage and can even be life-threatening in severe cases. The emergence of tissue engineering technology has led to the development of more possibilities for bladder repair and reconstruction, in which the selection of scaffolds is crucial. In recent years, a growing number of tissue-engineered bladder scaffolds have been constructed. Therefore, this paper will discuss the development of tissue-engineered bladder scaffolds and will further analyze the limitations of and challenges encountered in bladder reconstruction.

The Significance of Biomechanics and Scaffold Structure for Bladder Tissue Engineering

Current approaches for bladder reconstruction surgery are associated with many morbidities. Tissue engineering is considered an ideal approach to create constructs capable of restoring the function of the bladder wall. However, many constructs to date have failed to create a sufficient improvement in bladder capacity due to insufficient neobladder compliance. This review evaluates the biomechanical properties of the bladder wall and how the current reconstructive materials aim to meet this need. To date, limited data from mechanical testing and tissue anisotropy make it challenging to reach a consensus on the native properties of the bladder wall. Many of the materials whose mechanical properties have been quantified do not fall within the range of mechanical properties measured for native bladder wall tissue. Many promising new materials have yet to be mechanically quantified, which makes it difficult to ascertain their likely effectiveness. The impact of scaffold structures and the long-term effect of implanting these materials on their inherent mechanical properties are areas yet to be widely investigated that could provide important insight into the likely longevity of the neobladder construct. In conclusion, there are many opportunities for further investigation into novel materials for bladder reconstruction. Currently, the field would benefit from a consensus on the target values of key mechanical parameters for bladder wall scaffolds.

Comparative characteristic study from bone marrow-derived mesenchymal stem cells

Tissue engineering has been extensively investigated and proffered to be a potential platform for novel tissue regeneration. The utilization of mesenchymal stem cells (MSCs) from various sources has been widely explored and compared. In this regard, MSCs derived from bone marrow have been proposed and described as a promising cell resource due to their high yield of isolated cells with colony-forming potential, self-renewal capacity, MSC surface marker expression, and multi-lineage differentiation capacities in vitro. However, there is evidence for bone marrow MSCs (BM-MSCs) both in vitro and in vivo from different species presenting identical and distinct potential stemness characteristics. In this review, the fundamental knowledge of the growth kinetics and stemness properties of BM-MSCs in different animal species and humans are compared and summarized. Finally, to provide a full perspective, this review will procure results of current information studies focusing on the use of BM-MSCs in clinical practice.

Non-Muscular Invasive Bladder Cancer: Re-envisioning Therapeutic Journey from Traditional to Regenerative Interventions

Non-muscular invasive bladder cancer (NMIBC) is one of the most common cancer and major cause of economical and health burden in developed countries. Progression of NMIBC has been characterized as low-grade (Ta) and high grade (carcinoma in situ and T1). The current surgical intervention for NMIBC includes transurethral resection of bladder tumor; however, its recurrence still remains a challenge. The BCG-based immunotherapy is much effective against low-grade NMIBC. BCG increases the influx of T cells at bladder cancer site and inhibits proliferation of bladder cancer cells. The chemotherapy is another traditional approach to address NMIBC by supplementing BCG. Notwithstanding, these current therapeutic measures possess limited efficacy in controlling NMIBC, and do not provide comprehensive long-term relief. Hence, biomaterials and scaffolds seem an effective medium to deliver therapeutic agents for restructuring bladder post-treatment. The regenerative therapies such as stem cells and PRP have also been explored for possible solution to NMIBC. Based on above-mentioned approaches, we have comprehensively analyzed therapeutic journey from traditional to regenerative interventions for the treatment of NMIBC.

Therapeutic potential of adipose-derived mesenchymal stem cell exosomes in tissue-engineered bladders

Mesenchymal stem cells (MSCs) are a therapeutic tool for tissue engineering. However, many studies have recently shown that the therapeutic effects of MSCs are mediated by paracrine signaling and their secretory factors rather than their multidirectional differentiation ability. Exosomes isolated from the conditioned medium of MSCs are considered the main intercellular communication medium between MSCs and their target cells. Exosomes have been utilized in a novel cell-free therapy strategy that has attracted much attention. In this study, we evaluated the effects of a new cell-free tissue-engineered bladder (bladder acellular matrix combined with adipose-derived mesenchymal stem cell exosomes (AMEs)) in vivo and in vitro to prove that AMEs promoted tissue regeneration and functional recovery in a rat bladder replacement model.

Adipose Stromal Cells Enhance Decellularized Adipose Tissue Remodeling Through Multimodal Mechanisms

Decellularized adipose tissue (DAT) scaffolds represent a promising cell-instructive platform for soft tissue engineering. While recent work has highlighted that mesenchymal stromal cells, including adipose-derived stromal cells (ASCs), can be combined with decellularized scaffolds to augment tissue regeneration, the mechanisms involved require further study. The objective of this work was to probe the roles of syngeneic donor ASCs and host-derived macrophages in tissue remodeling of DAT scaffolds within an immunocompetent mouse model. Dual transgenic reporter mouse strains were employed to track and characterize the donor ASCs and host macrophages within the DAT implants. More specifically, ASCs isolated from dsRed mice were seeded on DAT scaffolds, and the seeded and unseeded control scaffolds were implanted subcutaneously into MacGreen transgenic mice for up to 8 weeks. ASC seeding was shown to augment cell infiltration into the DAT implants at 8 weeks, and this was linked to significantly enhanced angiogenesis relative to the unseeded controls. Immunohistochemical staining demonstrated long-term retention of the syngeneic donor ASCs over the duration of the 8-week study, providing evidence that the DAT scaffolds are a cell-supportive delivery platform. Notably, newly formed adipocytes within the DAT implants were not dsRed⁺, indicating that the donor ASCs supported fat formation through indirect mechanisms. Immunohistochemical tracking of host macrophages through costaining for enhanced green fluorescent protein with the macrophage marker Iba1 revealed that ASC seeding significantly increased the number of infiltrating macrophages within the DAT implants at 3 weeks, while the fraction of macrophages relative to the total cellular infiltrate was similar between the groups at 1, 3, and 8 weeks. Consistent with the tissue remodeling response that was observed, western blotting demonstrated that there was significantly augmented expression of CD163 and CD206, markers of constructive M2-like macrophages, within the ASC-seeded DAT implants. Overall, our results demonstrate that exogenous ASCs enhance tissue regeneration within DAT scaffolds indirectly through multimodal mechanisms that include host cell recruitment and immunomodulation. These data provide further evidence to support the use of decellularized scaffolds as a delivery platform for ASCs in tissue engineering.

Application of Adult and Pluripotent Stem Cells in Interstitial Cystitis/Bladder Pain Syndrome Therapy: Methods and Perspectives

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a multifactorial, chronic disease without definite etiology characterized by bladder-related pelvic pain. IC/BPS is associated with pain that negatively affects the quality of life. There are various therapeutic approaches against IC/BPS. However, no efficient therapeutic agent against IC/BPS has been discovered yet. Urothelium dysfunction is one of the key factors of IC/BPS-related pathogenicity. Stem cells, including adult stem cells (ASCs) and pluripotent stem cells (PSCs), such as embryonic stem cells (ESCs) and induced PSCs (iPSCs), possess the abilities of self-renewal, proliferation, and differentiation into various cell types, including urothelial and other bladder cells. Therefore, stem cells are considered robust candidates for bladder regeneration. This review provides a brief overview of the etiology, pathophysiology, diagnosis, and treatment of IC/BPS as well as a summary of ASCs and PSCs. The potential of ASCs and PSCs in bladder regeneration via differentiation into bladder cells or direct transplantation into the bladder and the possible applications in IC/BPS therapy are described in detail. A better understanding of current studies on stem cells and bladder regeneration will allow further improvement in the approaches of stem cell applications for highly efficient IC/BPS therapy.

A clinical-grade acellular matrix for esophageal replacement

In pathologies of the esophagus such as esophageal atresia, cancers, and caustic injuries, methods for full thickness esophageal replacement require the sacrifice of healthy intra-abdominal organs such as the stomach and the colon and are associated with high morbidity, mortality, and poor functional results. To overcome these problems, tissue engineering methods are developed to create a substitute with scaffolds and cells. The aim of this study was to develop a simple and safe decellularization process in order to obtain a clinical grade esophageal extracellular matrix. Following the decontamination step, porcine esophagi were decellularized in a bioreactor with sodium dodecyl sulfate and ethylenediaminetetraacetic acid for 3 days and were rinsed with deionized water. DNA was eliminated by a 3-hr DNase treatment. To remove any residual detergent, the matrix was then incubated with an absorbing resin. The resulting porcine esophageal matrix was characterized by the assessment of the efficiency of the decellularization process (DNA quantification), evaluation of sterility and absence of cytotoxicity, and its composition and biomechanical properties, as well as the possibility to be reseeded with mesenchymal stem cells. Complete decellularization with the preservation of the general structure, composition, and biomechanical properties of the native esophageal matrix was obtained. Sterility was maintained throughout the process, and the matrix showed no cytotoxicity. The resulting matrix met clinical grade criteria and was successfully reseeded with mesenchymal stem cells..

Premature ovarian failure and tissue engineering

Premature ovarian failure (POF) usually happens former to the age of 40 and affects the female physiological state premenopausal period. In this condition, ovaries stop working long before the expected menopausal time. Of diagnostic symptoms of the disease, one can mention amenorrhea and hypoestrogenism. The cause of POF in most cases is idiopathic; however, cancer therapy may also cause POF. Commonly utilized therapies such as hormone therapy, in-vitro activation, and regenerative medicine are the most well-known treatments for POF. Hence, these therapies may be associated with some complications. The aim of the present study is to discuss the beneficial effects of tissue engineering for fertility rehabilitation in patients with POF as a newly emerging therapy.

Tissue Engineering and Stem Cell Therapy in Pediatric Urology

The rapidly expanding field of tissue engineering along with stem cell therapy has a promising future in pediatric urological conditions. The initial struggle seemed difficult in renal regeneration but a functional biounit has been developed. Urine excretion has been demonstrated successfully from stem cell-generated embryonic kidneys. Three-dimensional (3D) stem cell-derived organoids are the new paradigm in research. Techniques to regenerate bladder tissue have reached the clinic, and the urethra is close behind. 3D bioprinted urethras would soon be available. Artificial germ cells produced from mouse pluripotent stem cells have been shown to give rise to live progeny. Myoblast and fibroblast therapy has been safely and effectively used for urinary incontinence. Stress urinary incontinence has been clinically treated with muscle-derived stem cells. Skeletal muscle-derived stem cells have been shown to get converted into smooth muscle cells when implanted into the corpora cavernosa in animal models. This review encompasses the various experimental and clinical developments in this field that can benefit pediatric urological conditions with the contemporary developments in the field.

Mesenchymal stromal cells modulate the molecular pattern of healing process in tissue-engineered urinary bladder: the microarray data

BACKGROUND

Molecular mechanisms underlying the regenerative process induced by stem cells in tissue-engineered urinary bladder are poorly explained. The study was performed to explore the pathways associated with regeneration process in the urinary bladder reconstructed with adipose tissue-derived mesenchymal stromal cells (ASCs).

METHODS

Rat urinary bladders were reconstructed with bladder acellular matrix (BAM) (n = 52) or BAM seeded with adipose tissue-derived mesenchymal stromal cells (ASCs) (n = 52). The process of bladder healing was analyzed at 7, 30, 90, and 180 days postoperatively using macroscopic histologic and molecular techniques. Gene expression was analyzed by microarrays and confirmed by real-time PCR.

RESULTS

Numerous differentially expressed genes (DEGs) were identified between the bladders augmented with BAM seeded with ASCs or BAM only. Pathway analysis of DEGs allows to discover numerous pathways among them Hedgehog, TGF-β, Jak-STAT, PI3-Akt, and Hippo modulated by ASCs during the healing process of tissue-engineered urinary bladder. Real-time PCR analysis confirmed upregulation of genes involved in the Hedgehog signaling pathway including Shh, Gli1, Smo, Bmp2, Bmp4, Wnt2, Wnt2b, Wnt4, Wnt5a, and Wnt10 in urinary bladders reconstructed with ASC-seeded grafts.

CONCLUSION

The study provided the unequivocal evidence that ASCs change the molecular pattern of healing in tissue-engineered urinary bladder and indicated which signaling pathways triggered by ASCs can be associated with the regenerative process. These pathways can be used as targets in the future studies on induced urinary bladder regeneration. Of particular interest is the Hedgehog signaling pathway that has been upregulated by ASCs during healing of tissue-engineered urinary bladder.

Improved bladder smooth muscle cell differentiation of the mesenchymal stem cells when grown on electrospun polyacrylonitrile/polyethylene oxide nanofibrous scaffold

Reconstruction of the bladder wall plays an important role in improving its function in patients with urinary bladder dysfunction. Tissue engineering has been trying to introduce biocompatible nanofibers as scaffolds for bladder wall matrix substitutes. In this study a composite nanofibrous scaffold was fabricated from polyacrylonitrile (PAN) and polyethylene oxide (PEO) blend by electrospinning method and then its morphological and mechanical characteristics was evaluated by scanning electron microscopy (SEM), tensile, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Then smooth muscle cell (SMC) differentiation supportive capacity of PAN-PEO nanofibers was investigated by culturing of human adipose tissue-derived mesenchymal stem cells (AT-MSCs) on this scaffold and then its differentiation potential in different groups was investigated using SMC-related gene and protein markers. SEM and MTT results demonstrated that PAN-PEO supported AT-MSCs attachment, growth and proliferation, especially at early times after cell seeding. The obtained results from real-time reverse transcription polymerase chain reaction revealed that collagen-I-α1, collagen-III-α1, α-smooth muscle actin (α-SMA), calponin1, SM22α, caldesmon1, elastin, and myosin heavy chain (MHC) genes were expressed in AT-MSCs cultured on PAN-PEO significantly higher than those stem cells that cultured on the culture plate as a control. In addition α-SMA and MHC proteins were also expressed in AT-MSCs cultured on PAN-PEO significantly higher than control. According to the results PAN-PEO nanofibrous scaffold showed a positive AT-MSCs-seeded PAN-PEO has a great promising potential to use in bladder tissue engineering applications.

Therapeutic strategies involving uterine stem cells in reproductive medicine

PURPOSE OF REVIEW

The current review provides an update on recent advances in stem cell biology relevant to female reproduction.

RECENT FINDINGS

Stem cells are undifferentiated cells that often serve as a reservoir of cells to regenerate tissue in settings or injury or cell loss. The endometrium has progenitor stem cells that can replace all of the endometrium during each menstrual cycle. In addition, multipotent endometrial cells replace these progenitor cells when depleted. Recruitment of stem cells from outside of the uterus occurs in setting of increased demand such as ischemia or injury. Bone marrow-derived multipotent stem cells are recruited to the uterus by estrogen or injury-induced expression of the chemokine CXCL12. In the setting of overwhelming injury, especially in the setting of low estrogen levels, there may be insufficient stem cell recruitment to adequately repair the uterus resulting in conditions such as Asherman syndrome or other endometrial defects. In contrast, excessive recruitment of stem cells underlies endometriosis. Enhanced understanding of stem-cell mobilization, recruitment, and engraftment has created the possibility of improved therapy for endometrial defects and endometriosis through enhanced manipulation of stem-cell trafficking. Further, the normal endometrium is a rich source of multipotent stem cells that can be used for numerous applications in regenerative medicine beyond reproduction.

SUMMARY

A better understanding of reproductive stem-cell biology may allow improved treatment of endometrial disease such as Asherman syndrome and other endometrial receptivity defects. Inhibiting stem-cell mobilization may also be helpful in endometriosis therapy. Finally, endometrial derived multipotent stem cells may play a crucial role in cell therapy for regenerative medicine.

Does the Mesenchymal Stem Cell Source Influence Smooth Muscle Regeneration in Tissue-Engineered Urinary Bladders?

A variety of tissue engineering techniques utilizing different cells and biomaterials are currently being explored to construct urinary bladder walls de novo, but so far no approach is clearly superior. The aim of this study was to determine whether mesenchymal stem cells (MSCs) isolated from different sources, (bone marrow [BM-MSCs] and adipose tissue [ADSCs]), differ in their potential to regenerate smooth muscles in tissue-engineered urinary bladders and to determine an optimal number of MSCs for urinary bladder smooth muscle regeneration. Forty-eight rats underwent hemicystectomy and bladder augmentation with approximately 0.8 cm² graft. In the first and second groups, urinary bladders were reconstructed with small intestinal submucosa (SIS) seeded with 10 × 10⁶ or 4 × 10⁶ ADSCs/cm², respectively. In the third and fourth groups, urinary bladders were augmented with SIS seeded with 10 × 10⁶ or 4 × 10⁶ BM-MSCs/cm², respectively. In the fifth group, urinary bladders were augmented with SIS without cells. The sixth group (control) was left intact. Smooth muscle regeneration was evaluated by real-time polymerase chain reaction (RT-PCR) and histological examinations. Histologically, there were no significant differences between urinary bladders augmented with ADSCs and BM-MSCs, but there was a marked increase in smooth muscle formation in bladders augmented with grafts seeded with MSCs in higher density (10 × 10⁶/cm²) compared to lower density (4 × 10⁶/cm²). Molecular analysis revealed that bladders reconstructed with ADSC-seeded grafts expressed higher levels of smooth muscle myosin heavy chain, caldesmon, and vinculin. Bladders augmented with unseeded SIS were fibrotic and devoid of smooth muscles. ADSCs and BM-MSCs have comparable smooth muscle regenerative potential, but the number of MSCs used for graft preparation significantly affects the smooth muscle content in tissue-engineered urinary bladders.

Circumferential Esophageal Replacement by a Tissue-engineered Substitute Using Mesenchymal Stem Cells: An Experimental Study in Mini Pigs

Tissue engineering appears promising as an alternative technique for esophageal replacement. Mesenchymal stem cells (MSCs) could be of interest for esophageal regeneration. Evaluation of the ability of an acellular matrix seeded with autologous MSCs to promote tissue remodeling toward an esophageal phenotype after circumferential replacement of the esophagus in a mini pig model. A 3 cm long circumferential replacement of the abdominal esophagus was performed with an MSC-seeded matrix (MSC group, n = 10) versus a matrix alone (control group, n = 10), which has previously been matured into the great omentum. The graft area was covered with an esophageal removable stent. A comparative histological analysis of the graft area after animals were euthanized sequentially is the primary outcome of the study. Histological findings after maturation, overall animal survival, and postoperative morbidity were also compared between groups. At postoperative day 45 (POD 45), a mature squamous epithelium covering the entire surface of the graft area was observed in all the MSC group specimens but in none of the control group before POD 95. Starting at POD 45, desmin positive cells were seen in the graft area in the MSC group but never in the control group. There were no differences between groups in the incidence of surgical complications and postoperative death. In this model, MSCs accelerate the mature re-epitheliazation and early initiation of muscle cell colonization. Further studies will focus on the use of cell tracking tools in order to analyze the becoming of these cells and the mechanisms involved in this tissue regeneration.

Understanding the role of mesenchymal stem cells in urinary bladder regeneration-a preclinical study on a porcine model

BACKGROUND

The tissue engineering of urinary bladder advances rapidly reflecting clinical need for a new kind of therapeutic solution for patients requiring urinary bladder replacement. Majority of the bladder augmentation studies have been performed in small rodent or rabbit models. Insufficient number of studies examining regenerative capacity of tissue-engineered graft in urinary bladder augmentation in a large animal model does not allow for successful translation of this technology to the clinical setting. The aim of this study was to evaluate the role of adipose-derived stem cells (ADSCs) in regeneration of clinically significant urinary bladder wall defect in a large animal model.

METHODS

ADSCs isolated from a superficial abdominal Camper's fascia were labeled with PKH-26 tracking dye and subsequently seeded into bladder acellular matrix (BAM) grafts. Pigs underwent hemicystectomy followed by augmentation cystoplasty with BAM only (n = 10) or BAM seeded with autologous ADSCs (n = 10). Reconstructed bladders were subjected to macroscopic, histological, immunofluoresence, molecular, and radiological evaluations at 3 months post-augmentation.

RESULTS

Sixteen animals (n = 8 for each group) survived the 3-month follow-up without serious complications. Tissue-engineered bladder function was normal without any signs of post-voiding urine residual in bladders and in the upper urinary tracts. ADSCs enhanced regeneration of tissue-engineered urinary bladder but the process was incomplete in the central graft region. Only a small percentage of implanted ADSCs survived and differentiated into smooth muscle and endothelial cells.

CONCLUSIONS

The data demonstrate that ADSCs support regeneration of large defects of the urinary bladder wall but the process is incomplete in the central graft region. Stem cells enhance urinary bladder regeneration indirectly through paracrine effect.

Bladder augmentation in children: current problems and experimental strategies for reconstruction

Bladder augmentation is a demanding surgical procedure and exclusively offered for selected children and has only a small spectrum of indications. Paediatric bladder voiding dysfunction occurs either on a basis of neurological dysfunction caused by congenital neural tube defects or on a basis of rare congenital anatomic malformations. Neurogenic bladder dysfunction often responds well to a combination of specific drugs and/or intermittent self-catheterization. However, selected patients with spinal dysraphism and children with congenital malformations like bladder exstrophy and resulting small bladder capacity might require bladder augmentation. Ileocystoplasty is the preferred method of bladder augmentation to date. Because of the substantial long-and short-term morbidity of augmentation cystoplasty, recent studies have tried to incorporate new techniques and technologies, such as the use of biomaterials to overcome or reduce the adverse effects. In this regard, homografts and allografts have been implemented in bladder augmentation with varying results, but recent studies have shown promising data in terms of proliferation of urothelium and muscle cells by using biological silk grafts.

Adipose-derived stem-cell-implanted poly(ϵ-caprolactone)/chitosan scaffold improves bladder regeneration in a rat model

AIM

The study investigated the feasibility of seeding adipose-derived stem cells (ASCs) onto a poly(ϵ-caprolactone)/chitosan (PCL/CS) scaffold for bladder reconstruction using a rat model of bladder augmentation.

MATERIALS & METHODS

In the experimental group, the autologous ASCs were seeded onto the PCL/CS scaffold for bladder augmentation. An unseeded scaffold was used for bladder augmentation as control group. The sham group was also set.

RESULT

8 weeks after implantation, more densely smooth muscles were detected in the experimental group with a larger bladder capacity and more intensive blood vessels. Immunofluorescence staining demonstrated that some of the smooth muscle cells were transdifferentiated from the ASCs.

CONCLUSION

Our findings indicated that ASC-seeded PCL/CS may be a potential scaffold for bladder tissue engineering.

Decellularized Matrices As Cell-Instructive Scaffolds to Guide Tissue-Specific Regeneration

Decellularized scaffolds are promising clinically translational biomaterials that can be applied to direct cell responses and promote tissue regeneration. Bioscaffolds derived from the extracellular matrix (ECM) of decellularized tissues can naturally mimic the complex extracellular microenvironment through the retention of compositional, biomechanical, and structural properties specific to the native ECM. Increasingly, studies have investigated the use of ECM-derived scaffolds as instructive substrates to recapitulate properties of the stem cell niche and guide cell proliferation, paracrine factor production, and differentiation in a tissue-specific manner. Here, we review the application of decellularized tissue scaffolds as instructive matrices for stem or progenitor cells, with a focus on the mechanisms through which ECM-derived scaffolds can mediate cell behavior to promote tissue-specific regeneration. We conclude that although additional preclinical studies are required, ECM-derived scaffolds are a promising platform to guide cell behavior and may have widespread clinical applications in the field of regenerative medicine.

A Gingiva-Derived Mesenchymal Stem Cell-Laden Porcine Small Intestinal Submucosa Extracellular Matrix Construct Promotes Myomucosal Regeneration of the Tongue

In the oral cavity, the tongue is the anatomic subsite most commonly involved by invasive squamous cell carcinoma. Current treatment protocols often require significant tissue resection to achieve adequate negative margins and optimal local tumor control. Reconstruction of the tongue while preserving and/or restoring its critical vocal, chewing, and swallowing functions remains one of the major challenges in head and neck oncologic surgery. We investigated the in vitro feasibility of fabricating a novel combinatorial construct using porcine small intestinal submucosa extracellular matrix (SIS-ECM) and human gingiva-derived mesenchymal stem cells (GMSCs) as a GMSC/SIS-ECM tissue graft for the tongue reconstruction. We developed a rat model of critical-sized myomucosal defect of the tongue that allowed the testing of therapeutic effects of an acellular SIS-ECM construct versus a GMSC/SIS-ECM construct on repair and regeneration of the tongue defect. We showed that the GMSC/SIS-ECM construct engrafted at the host recipient site, promoted soft tissue healing, and regenerated the muscular layer, compared to the SIS-ECM alone or nontreated defect controls. Furthermore, our results revealed that transplantation of the GMSC/SIS-ECM construct significantly increased the expression of several myogenic transcriptional factors and simultaneously suppressed the expression of type I collagen at the wounded area of the tongue. These compelling findings suggest that, unlike the tongue contracture and fibrosis of the nontreated defect group, transplantation of the combinatorial GMSC/SIS-ECM constructs accelerates wound healing and muscle regeneration and maintains the overall tongue shape, possibly by both enhancing the function of endogenous skeletal progenitor cells and suppressing fibrosis. Together, our findings indicate that GMSC/SIS-ECM potentially served as a myomucosal graft for tongue reconstruction postsurgery of head and neck cancer.

CD44 fucosylation on mesenchymal stem cell enhances homing and macrophage polarization in ischemic kidney injury

The lack of homing ability possibly reduces the healing potential of bone-marrow-derived mesenchymal stem cells (MSCs). Therefore, transforming native CD44 on MSCs into a hematopoietic cell E-/L-selectin ligand (HCELL) that possesses potent E-selectin affinity might enhance the homing and regenerative abilities of MSCs. Through fucosyltransferase VI (FTVI) transfection, MSCs were fucosylated on N-glycans of CD44 to become HCELL positive, thus interacting with E-selectin on injured endothelial cells. HCELL expression facilitated MSC homing in kidneys within 24h after injury and reduced lung stasis. An in vitro adhesion assay revealed that transfection enhanced the association between MSCs and hypoxic endothelial cells. In mice treated with HCELL-positive MSCs, the injured kidneys exhibited clusters of homing MSCs, whereas MSCs were rarely observed in mouse kidneys treated with HCELL-negative MSCs. Most MSCs were initially localized at the renal capsule, and some MSCs later migrated inward between tubules. Most homing MSCs were in close contact with inflammatory cells without tubular transdifferentiation. Furthermore, HCELL-positive MSCs substantially alleviated renal injury, partly by enhancing the polarization of infiltrating macrophages. In conclusion, engineering the glycan of CD44 on MSCs through FTVI transfection might enhance renotropism and the regenerating ability of MSCs in ischemic kidney injury.

Stem Cells Applications in Regenerative Medicine and Disease Therapeutics

Regenerative medicine, the most recent and emerging branch of medical science, deals with functional restoration of tissues or organs for the patient suffering from severe injuries or chronic disease. The spectacular progress in the field of stem cell research has laid the foundation for cell based therapies of disease which cannot be cured by conventional medicines. The indefinite self-renewal and potential to differentiate into other types of cells represent stem cells as frontiers of regenerative medicine. The transdifferentiating potential of stem cells varies with source and according to that regenerative applications also change. Advancements in gene editing and tissue engineering technology have endorsed the ex vivo remodelling of stem cells grown into 3D organoids and tissue structures for personalized applications. This review outlines the most recent advancement in transplantation and tissue engineering technologies of ESCs, TSPSCs, MSCs, UCSCs, BMSCs, and iPSCs in regenerative medicine. Additionally, this review also discusses stem cells regenerative application in wildlife conservation.

Mesenchymal Stem Cell Seeding of Porcine Small Intestinal Submucosal Extracellular Matrix for Cardiovascular Applications

In this study, we investigate the translational potential of a novel combined construct using an FDA-approved decellularized porcine small intestinal submucosa extracellular matrix (SIS-ECM) seeded with human or porcine mesenchymal stem cells (MSCs) for cardiovascular indications. With the emerging success of individual component in various clinical applications, the combination of SIS-ECM with MSCs could provide additional therapeutic potential compared to individual components alone for cardiovascular repair. We tested the in vitro effects of MSC-seeding on SIS-ECM on resultant construct structure/function properties and MSC phenotypes. Additionally, we evaluated the ability of porcine MSCs to modulate recipient graft-specific response towards SIS-ECM in a porcine cardiac patch in vivo model. Specifically, we determined: 1) in vitro loading-capacity of human MSCs on SIS-ECM, 2) effect of cell seeding on SIS-ECM structure, compositions and mechanical properties, 3) effect of SIS-ECM seeding on human MSC phenotypes and differentiation potential, and 4) optimal orientation and dose of porcine MSCs seeded SIS-ECM for an in vivo cardiac application. In this study, histological structure, biochemical compositions and mechanical properties of the FDA-approved SIS-ECM biomaterial were retained following MSCs repopulation in vitro. Similarly, the cellular phenotypes and differentiation potential of MSCs were preserved following seeding on SIS-ECM. In a porcine in vivo patch study, the presence of porcine MSCs on SIS-ECM significantly reduced adaptive T cell response regardless of cell dose and orientation compared to SIS-ECM alone. These findings substantiate the clinical translational potential of combined SIS-ECM seeded with MSCs as a promising therapeutic candidate for cardiac applications.

Bone marrow mesenchymal stem cell therapy for voiding dysfunction

Lower urinary tract symptoms can significantly impact quality of life. Current standard treatments are not always effective and are associated with complications and side effects. The discovery of stem cells led to research into cell-based therapies for treatment of disorders of voiding dysfunction. Bone marrow mesenchymal stem cells are particularly promising given their ability to differentiate into a variety of cell types. Recent studies have investigated bone marrow stem cells to treat a number of functional voiding pathologies including bladder outlet obstruction, neurogenic bladder, and stress urinary incontinence. Experiments in tissue regeneration have also attempted to create artificial bladders and urethras. The purpose of this article is to critically review the literature regarding the use of bone marrow mesenchymal stem cells in treatment of voiding dysfunction.

Ex vivo construction of a novel model of bioengineered bladder mucosa: A preliminary study

OBJECTIVE

To generate and to evaluate ex vivo a novel model of bioengineered human bladder mucosa based on fibrin-agarose biomaterials.

METHODS

We first established primary cultures of stromal and epithelial cells from small biopsies of the human bladder using enzymatic digestion and selective cell culture media. Then, a bioengineered substitute of the bladder lamina propria was generated using cultured stromal cells and fibrin-agarose scaffolds, and the epithelial cells were then subcultured on top to generate a complete bladder mucosa substitute. Evaluation of this substitute was carried out by cell viability and histological analyses, immunohistochemistry for key epithelial markers and transmission electron microscopy.

RESULTS

The results show a well-configured stroma substitute with a single-layer epithelium on top. This substitute was equivalent to the control bladder mucosa. After 7 days of ex vivo development, the epithelial layer expressed pancytokeratin, and cytokeratins CK7, CK8 and CK13, as well as filaggrin and ZO-2, with negative expression of CK4 and uroplakin III. A reduction of the expression of CK8, filaggrin and ZO-2 was found at day 14 of development. An immature basement membrane was detected at the transition between the epithelium and the lamina propria, with the presence of epithelial hemidesmosomes, interdigitations and immature desmosomes.

CONCLUSIONS

The present results suggest that this model of bioengineered human bladder mucosa shared structural and functional similarities with the native bladder mucosa, although the epithelial cells were not fully differentiated ex vivo. We hypothesize that this bladder mucosa substitute could have potential clinical usefulness after in vivo implantation.

The potential utility of non-invasive imaging to monitor restoration of bladder structure and function following subtotal cystectomy (STC)

Background

Restoration of normal bladder volume and function (i.e., bioequivalent bladder) are observed within 8 weeks of performing subtotal cystectomy (STC; removal of ~70 % of the bladder) in 12-week old rats. For analysis of bladder function in rodents, terminal urodynamic approaches are largely utilized. In the current study, we investigated the potential for Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) scans to noninvasively track restoration of structure and function following STC.

Methods

Twelve week old female Fisher F344 rats underwent STC and were scanned via CT and/or MRI 2, 4, 8, and 12 weeks post-STC, followed by urodynamic testing. After euthanasia, bladders were excised for histological processing.

Results

MRI scans demonstrated an initial decline followed by a time-dependent increase to normal bladder wall thickness (BWT) by 8 weeks post-STC. Masson’s trichrome staining showed a lack of fibrosis post-STC, and also revealed that the percent of smooth muscle in the bladder wall at 2 and 4 weeks positively correlated with pre-operative baseline BWT. Moreover, increased BWT values before STC was predictive of improved bladder compliance at 2 and 4 weeks post-STC. Cystometric studies indicated that repeated MRI manipulation (i.e. bladder emptying) apparently had a negative impact on bladder capacity and compliance. A “window” of bladder volumes was identified 2 weeks post-STC via CT scanning that were commensurate with normal micturition pressures measured in the same animal 6 weeks later.

Conclusions

Taken together, the data indicate some limitations of “non-invasive” imaging to provide insight into bladder regeneration. Specifically, mechanical manipulation of the bladder during MRI appears to negatively impact the regenerative process per se, which highlights the importance of terminal cystometric studies.

The Role of Genetically Modified Mesenchymal Stem Cells in Urinary Bladder Regeneration

Recent studies have demonstrated that mesenchymal stem cells (MSCs) combined with CD34⁺ hematopoietic/stem progenitor cells (HSPCs) can function as surrogate urinary bladder cells to synergistically promote multi-faceted bladder tissue regeneration. However, the molecular pathways governing these events are unknown. The pleiotropic effects of Wnt5a and Cyr61 are known to affect aspects of hematopoiesis, angiogenesis, and muscle and nerve regeneration. Within this study, the effects of Cyr61 and Wnt5a on bladder tissue regeneration were evaluated by grafting scaffolds containing modified human bone marrow derived MSCs. These cell lines were engineered to independently over-express Wnt5a or Cyr61, or to exhibit reduced expression of Cyr61 within the context of a nude rat bladder augmentation model. At 4 weeks post-surgery, data demonstrated increased vessel number (~250 vs ~109 vessels/mm²) and bladder smooth muscle content (~42% vs ~36%) in Cyr61OX (over-expressing) vs Cyr61KD (knock-down) groups. Muscle content decreased to ~25% at 10 weeks in Cyr61KD groups. Wnt5aOX resulted in high numbers of vessels and muscle content (~206 vessels/mm² and ~51%, respectively) at 4 weeks. Over-expressing cell constructs resulted in peripheral nerve regeneration while Cyr61KD animals were devoid of peripheral nerve regeneration at 4 weeks. At 10 weeks post-grafting, peripheral nerve regeneration was at a minimal level for both Cyr61OX and Wnt5aOX cell lines. Blood vessel and bladder functionality were evident at both time-points in all animals. Results from this study indicate that MSC-based Cyr61OX and Wnt5aOX cell lines play pivotal roles with regards to increasing the levels of functional vasculature, influencing muscle regeneration, and the regeneration of peripheral nerves in a model of bladder augmentation. Wnt5aOX constructs closely approximated the outcomes previously observed with the co-transplantation of MSCs with CD34⁺ HSPCs and may be specifically targeted as an alternate means to achieve functional bladder regeneration.

Production of urothelium from pluripotent stem cells for regenerative applications

As bladder reconstruction strategies evolve, a feasible and safe source of transplantable urothelium becomes a major consideration for patients with advanced bladder disease, particularly cancer. Pluripotent stem cells, such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), are attractive candidates from which to derive urothelium as they renew and proliferate indefinitely in vitro and fulfill the non-autologous and/or non-urologic criteria, respectively, that is required for many patients. This review presents the latest advancements in differentiating urothelium from pluripotent stem cells in vitro in the context of current bladder tissue engineering strategies.

The endometrium as a source of mesenchymal stem cells for regenerative medicine

Stem cell therapies have opened new frontiers in medicine with the possibility of regenerating lost or damaged cells. Embryonic stem cells, induced pluripotent stem cells, hematopoietic stem cells, and mesenchymal stem cells have been used to derive mature cell types for tissue regeneration and repair. However, the endometrium has emerged as an attractive, novel source of adult stem cells that are easily accessed and demonstrate remarkable differentiation capacity. In this review, we summarize our current understanding of endometrial stem cells and their therapeutic potential in regenerative medicine.

Dynamic reciprocity in cell-scaffold interactions

Tissue engineering in urology has shown considerable promise. However, there is still much to understand, particularly regarding the interactions between scaffolds and their host environment, how these interactions regulate regeneration and how they may be enhanced for optimal tissue repair. In this review, we discuss the concept of dynamic reciprocity as applied to tissue engineering, i.e. how bi-directional signaling between implanted scaffolds and host tissues such as the bladder drives the process of constructive remodeling to ensure successful graft integration and tissue repair. The impact of scaffold content and configuration, the contribution of endogenous and exogenous bioactive factors, the influence of the host immune response and the functional interaction with mechanical stimulation are all considered. In addition, the temporal relationships of host tissue ingrowth, bioactive factor mobilization, scaffold degradation and immune cell infiltration, as well as the reciprocal signaling between discrete cell types and scaffolds are discussed. Improved understanding of these aspects of tissue repair will identify opportunities for optimization of repair that could be exploited to enhance regenerative medicine strategies for urology in future studies.

Virus integration and genome influence in approaches to stem cell based therapy for andro-urology

Despite the potential of stem cells in cell-based therapy, major limitations such as cell retention, ingrowth, and trans-differentiation after implantation remain. One technique for genetic modification of cells for tissue repair is the introduction of specific genes using molecular biology techniques, such as virus integration, to provide a gene that adds new functions to enhance cellular function, and to secrete trophic factors for recruiting resident cells to participate in tissue repair. Stem cells can be labeled to track cell survival, migration, and lineage. Increasing evidence demonstrates that cell therapy and gene therapy in combination remarkably improve differentiation of implanted mesenchymal stromal cells (MSCs), revascularization, and innervation in genitourinary tissues, especially to treat urinary incontinence, erectile dysfunction, lower urinary tract reconstruction, and renal failure. This review discusses the benefits, safety, side effects, and alternatives for using genetically modified MSCs in tissue regeneration in andro-urology.

Bladder tissue engineering: a literature review

PURPOSE OF REVIEW

In bladder cancer and neuro-bladder, reconstruction of the bladder requires bowel segment grafting for augmentation cystoplasty or neo-bladder creation. However, even if currently considered as the gold standard, it is associated with potentially severe short- and long-term adverse effects. Thus, bladder tissue engineering is a promising approach to bladder reconstruction.

RECENT FINDINGS

In the last few years, progress has been made with the development of new biomaterials for bladder tissue replacement and in deciphering the role of stem cells as well as their contribution to bladder scaffold integration and tissue regeneration.

SUMMARY

This review of recently published articles allows us to forecast the characteristics of efficient and safe bladder biomaterials. However, several factors, such as native bladder traits, the specific involvement of urine, and bladder tissue replacement indications, have to be assessed with caution before including bladder tissue engineering in clinical trials. Many authors agree that these challenging techniques could deliver significant benefits with clinical application, reducing morbidity and global long-term costs.

Biomatrices for bladder reconstruction

There is a demand for tissue engineering of the bladder needed by patients who experience a neurogenic bladder or idiopathic detrusor overactivity. To avoid complications from augmentation cystoplasty, the field of tissue engineering seeks optimal scaffolds for bladder reconstruction. Naturally derived biomaterials as well as synthetic and natural polymers have been explored as bladder substitutes. To improve regenerative properties, these biomaterials have been conjugated with functional molecules, combined with nanotechology, or seeded with exogenous cells. Although most studies reported complete and functional bladder regeneration in small-animal models, results from large-animal models and human clinical trials varied. For functional bladder regeneration, procedures for biomaterial fabrication, incorporation of biologically active agents, introduction of nanotechnology, and application of stem-cell technology need to be standardized. Advanced molecular and medical technologies such as next generation sequencing and magnetic resonance imaging can be introduced for mechanistic understanding and non-invasive monitoring of regeneration processes, respectively.

Tissue engineering of rat bladder using marrow-derived mesenchymal stem cells and bladder acellular matrix

Bladder replacement or augmentation is required in congenital malformations or following trauma or cancer. The current surgical solution involves enterocystoplasty but is associated with high complication rates. Strategies for bladder tissue engineering are thus actively sought to address this unmet clinical need. Because of the poor efficacy of synthetic polymers, the use of bladder acellular matrix (BAM) has been proposed. Indeed when cellular components are removed from xenogenic or allogeneic bladders, the extracellular matrix scaffold thus obtained can be used alone or in combination with stem cells. In this study, we propose the use of BAM seeded with marrow-derived mesenchymal stem cells (MSCs) for bladder tissue engineering. We optimized a protocol for decellularization of bladder tissue from different species including rat, rabbit and swine. We demonstrate the use of non-ionic detergents followed by nuclease digestion results in efficient decellularization while preserving the extracellular matrix. When MSCs were seeded on acellular matrix scaffold, they remained viable and proliferative while adopting a cellular phenotype consistent with their microenvironment. Upon transplantation in rats after partial cystectomy, MSC-seeded BAM proved superior to unseeded BAM with animals recovering nearly 100% normal bladder capacity for up to six months. Histological analyses also demonstrated increased muscle regeneration.