Histological changes induced by Polyglycolic-Acid (PGA) scaffolds seeded with autologous adipose or muscle-derived stem cells when implanted on rabbit bladder

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.

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.

Polymeric Implants for the Treatment of Intraocular Eye Diseases: Trends in Biodegradable and Non-Biodegradable Materials

Intraocular/Intravitreal implants constitute a relatively new method to treat eye diseases successfully due to the possibility of releasing drugs in a controlled and prolonged way. This particularity has made this kind of method preferred over other methods such as intravitreal injections or eye drops. However, there are some risks and complications associated with the use of eye implants, the body response being the most important. Therefore, material selection is a crucial factor to be considered for patient care since implant acceptance is closely related to the physical and chemical properties of the material from which the device is made. In this regard, there are two major categories of materials used in the development of eye implants: non-biodegradables and biodegradables. Although non-biodegradable implants are able to work as drug reservoirs, their surgical requirements make them uncomfortable and invasive for the patient and may put the eyeball at risk. Therefore, it would be expected that the human body responds better when treated with biodegradable implants due to their inherent nature and fewer surgical concerns. Thus, this review provides a summary and discussion of the most common non-biodegradable and biodegradable materials employed for the development of experimental and commercially available ocular delivery implants.

Stem Cells Seeded on Multilayered Scaffolds Implanted into an Injured Bladder Rat Model Improves Bladder Function

Background

To investigate whether human adipose-derived stem cells (hADSCs) seeded on multilayered poly (l-lactide-co-ɛ-caprolactone) (PLCL) sheets improve bladder function in a rat model of detrusor smooth muscle-removed bladder.

Methods

Male rats were randomly divided into 4 groups: Normal, injury (detrusor smooth muscle-removed bladder), PLCL (detrusor smooth muscle-removed bladder implanted with PLCL sheets), and PLCL + ADSC (detrusor smooth muscle-removed bladder implanted with PLCL sheets seeded with hADSCs). Four weeks after the treatment, physiological, histological, immunohistochemical, and immunoblot analyses were performed.

Results

hADSCs were compatible with PLCL sheets. Further, the physiological study of PLCL + ADSC group showed significant improvement in compliance and contractility suggesting the functional improvement of the bladder. Histological, immunohistochemical and immunoblot analyses revealed the uniform distribution of hADSCs in between PLCL sheets as well as differentiation of hADSCs into smooth muscle cells (SMC) which is illustrated by the expression of SMC markers.

Conclusion

hADSCs seeded on the multilayered PLCL sheets has the potential to differentiate into SMC, thus facilitating the recovery of compliance and contractility of the injured bladder.

Bioengineered bladder patches constructed from multilayered adipose-derived stem cell sheets for bladder regeneration

Cell-seeded scaffolds are a common route of cell transplantation for bladder repair and reconstruction. However, when cell suspensions are harvested, proteolytic enzymes often cause extracellular matrix damage and loss of intercellular junctions. To overcome this problem, we developed a bioengineered three-dimensional bladder patch comprising porous scaffolds and multilayered adipose-derived stem cell (ASC) sheets, and evaluated its feasibility for bladder regeneration in a rat model. Adipose-derived stem cells (ASCs) were labeled with ultrasmall super-paramagnetic iron oxide (USPIO) nanoparticles. ASC patches were constructed using multilayered USPIO-labeled ASC sheets and porous polyglycolic acid scaffolds. To monitor the distribution and localization of bioengineered bladder patches in live animals, magnetic resonance imaging (MRI) was performed 2 weeks, 4 weeks and 8 weeks after transplantation. The bladder regenerative potential of ASC patches was further evaluated by urodynamic and histological analysis. Scanning electron microscopy indicated that cell sheets adhered tightly to the scaffold. MRI showed hypointense signals that lasted up to 8 weeks at the site of USPIO-labeled ASC sheet transplants. Immunofluorescence demonstrated that these tissue-engineered bladder patches promoted regeneration of urothelium, smooth muscle, neural cells and blood vessels. Urodynamic testing revealed that the ASC patch restored bladder function with augmented capacity. The USPIO-labeled ASC patch provides a promising perspective on image-guided tissue engineering and holds great promise as a safe and effective therapeutic strategy for bladder regeneration. STATEMENT OF SIGNIFICANCE: Adipose-derived stem cell (ASC) sheets avoid enzymatic dissociation and preserve the cell-to-cell interactions and extracellular matrix (ECM) proteins, which exhibit great potential for tissue regeneration. In this study, we developed a bioengineered three-dimensional bladder patch comprising porous scaffolds and multilayered ASC sheets, and evaluated its feasibility for bladder regeneration in a rat model. Tissue-engineered bladder patches restored bladder function and promoted regeneration of urothelium, smooth muscle, neural cells and blood vessels. Moreover, ultrasmall super-paramagnetic iron oxide (USPIO)-labeled bladder patches can be dynamically monitored in vivo by noninvasive MRI for long periods of time. Therefore, The USPIO-labeled bladder patch provides a promising image-guided therapeutic strategy for bladder regeneration.

A modified preplate technique for efficient isolation and proliferation of mice muscle-derived stem cells

We modified an existing protocol to develop a more efficient method to acquire and culture muscle-derived stem cells (MDSCs) and compared the characteristics of cells obtained from the two methods. This method is based on currently used multistep enzymatic digestion and preplate technique. During the replating process, we replaced the traditional medium with isolation medium to promote fibroblast-like cell adherence at initial replating step, which shortened the purifying duration by up to 4 days. Moreover, we modified the culture container to provide a stable microenvironment that promotes MDSC adherence. We compared the cell morphology, growth curve and the expression of specific markers (Sca-1, CD34, PAX7 and Desmin) between the two cell groups separately obtained from the two methods. Afterwards, we compared the neural differentiation capacity of MDSCs with other muscle-derived cell lineages. The protocol developed here is a fast and effective method to harvest and purify MDSCs from mice limb skeletal muscle.

Adipogenic differentiation of human adipose derived mesenchymal stem cells in 3D architectured gelatin based hydrogels (ArcGel)

Polymeric matrices mimicking multiple functions of the ECM are expected to enable a material induced regeneration of tissues. Here, we investigated the adipogenic differentiation of human adipose derived mesenchymal stem cells (hADSCs) in a 3D architectured gelatin based hydrogel (ArcGel) prepared from gelatin and L-lysine diisocyanate ethyl ester (LDI) in an one-step process, in which the formation of an open porous morphology and the chemical network formation were integrated. The ArcGel was designed to support adipose tissue regeneration with its 3D porous structure, high cell biocompatibility, and mechanical properties compatible with human subcutaneous adipose tissue. The ArcGel could support initial cell adhesion and survival of hADSCs. Under static culture condition, the cells could migrate into the inner part of the scaffold with a depth of 840±120 μm after 4 days, and distributed in the whole scaffold (2 mm in thickness) within 14 days. The cells proliferated in the scaffold and the fold increase of cell number after 7 days of culture was 2.55±0.08. The apoptotic rate of hADSCs in the scaffold was similar to that of cells maintained on tissue culture plates. When cultured in adipogenic induction medium, the hADSCs in the scaffold differentiated into adipocytes with a high efficiency (93±1%). Conclusively, this gelatin based 3D scaffold presented high cell compatibility for hADSC cultivation and differentiation, which could serve as a potential implant material in clinical applications for adipose tissue reparation and regeneration.

Trilayer Three-Dimensional Hydrogel Composite Scaffold Containing Encapsulated Adipose-Derived Stem Cells Promotes Bladder Reconstruction via SDF-1α/CXCR4 Pathway

Bladder acellular matrix graft-alginate dialdehyde-gelatin hydrogel-silk mesh (BAMG-HS) encapsulated with adipose-derived stem cells (ASCs) was evaluated in a rat model of augmentation cystoplasty, including BAMG-HS-ASCs (n = 18, subgroup n = 6 for 2, 4, and 12 weeks), acellular BAMG-HS (n = 6 for 12 weeks) and cystotomy control (n = 6 for 12 weeks) groups. Equipped with good cytocompatibility and superior mechanical properties (elastic modulus: 5.33 ± 0.96 MPa, maximum load: 28.90 ± 0.69 N), BAMG-HS acted a trilayer "sandwich" scaffold with minimal interference in systemic homeostasis. ASCs in BAMG-HS promoted morphological and histological bladder restoration by accelerating scaffold degradation (p < 0.05), ameliorating fibrosis (p < 0.05) and inflammation (p < 0.01). Additionally, ASCs facilitated the recovery of bladder function by enhancing smooth muscle regeneration (p < 0.05), innervation (p < 0.01) and angiogenesis (p < 0.001). Except for a small number of endothelium-differentiated ASCs, the pro-angiogenic effects of ASCs were mainly related to ERK1/2 phosphorylation in the downstream of SDF-1α/CXCR4 pathway.

Adipose-derived stem cells-seeded bladder acellular matrix graft-silk fibroin enhances bladder reconstruction in a rat model

The unfavourable clinical outcomes of host cell-seeded scaffolds for bladder augmentation warrant improved bioactive biomaterials. This study aimed to examine the feasibility of adipose-derived stem cells (ASCs)-seeded bilayer bladder acellular matrix graft (BAMG)-silk fibroin (SF) scaffold in enhancing bladder reconstruction. Sprague Dawley rats were randomly divided into three groups: the BAMG-SF-ASCs group, the acellular BAMG-SF group and the cystotomy group. The BAMG-SF-ASCs group was sampled at 2, 4 and 12 weeks, and compared with the other groups at 12 weeks. In the BAMG-SF-ASCs group, the normal bladder contour was reformed similar to that in the cystotomy group, with abundant urothelium and smooth muscle regeneration, as well as a suitable scaffold degradation speed, and trivial fibrosis and inflammation. The ASCs seeded in BAMG-SF were maintained in the regenerated region during the 12-week experimental period and significantly enhanced the vessel density, nerve regeneration and bladder function compared with acellular BAMG-SF. In addition, the BAMG-SF-ASCs group presented elevated levels of SDF-1α, VEGF and their receptors, with an obvious increase in ERK 1/2 phosphorylation. BAMG-SF is a promising biomaterial for ASCs seeding to facilitate bladder augmentation and demonstrated an enhanced angiogenic potential possibly related to the SDF-1α/CXCR4 pathway via ERK 1/2 activation.

Comparison of morphological and functional restoration between asymmetric bilayer chitosan and bladder acellular matrix graft for bladder augmentation in a rat model

Asymmetric bilayer chitosan promoted bladder reconstruction with enhanced smooth muscle regeneration and angiogenesis, and functional restoration with augmented bladder capacity.

Adipose regeneration and implications for breast reconstruction: update and the future

The evolution of breast reconstruction and management of breast cancer has evolved significantly since the earliest descriptions in the Edwin Smith Papyrus (3,000 BC). The development of surgical and scientific expertise has changed the way that women are managed, and plastic surgeons are now able to offer a wide range of reconstructive options to suit individual needs. Beyond the gold standard autologous flap based reconstructions, regenerative therapies promise the elimination of donor site morbidity whilst providing equivalent aesthetic and functional outcomes. Future research aims to address questions regarding ideal cell source, optimisation of scaffold composition and interaction of de novo adipose tissue in the microenvironment of breast cancer.

Human Urine-derived Stem Cells Seeded Surface Modified Composite Scaffold Grafts for Bladder Reconstruction in a Rat Model

We conducted this study to investigate the synergistic effect of human urine-derived stem cells (USCs) and surface modified composite scaffold for bladder reconstruction in a rat model. The composite scaffold (Polycaprolactone/Pluronic F127/3 wt% bladder submucosa matrix) was fabricated using an immersion precipitation method, and heparin was immobilized on the surface via covalent conjugation. Basic fibroblast growth factor (bFGF) was loaded onto the heparin-immobilized scaffold by a simple dipping method. In maximal bladder capacity and compliance analysis at 8 weeks post operation, the USCs-scaffold(heparin-bFGF) group showed significant functional improvement (2.34 ± 0.25 mL and 55.09 ± 11.81 µL/cm H2O) compared to the other groups (2.60 ± 0.23 mL and 56.14 ± 9.00 µL/cm H2O for the control group, 1.46 ± 0.18 mL and 34.27 ± 4.42 µL/cm H2O for the partial cystectomy group, 1.76 ± 0.22 mL and 35.62 ± 6.69 µL/cm H2O for the scaffold group, and 1.92 ± 0.29 mL and 40.74 ± 7.88 µL/cm H2O for the scaffold(heparin-bFGF) group, respectively). In histological and immunohistochemical analysis, the USC-scaffold(heparin-bFGF) group showed pronounced, well-differentiated, and organized smooth muscle bundle formation, a multi-layered and pan-cytokeratin-positive urothelium, and high condensation of submucosal area. The USCs seeded scaffold(heparin-bFGF) exhibits significantly increased bladder capacity, compliance, regeneration of smooth muscle tissue, multi-layered urothelium, and condensed submucosa layers at the in vivo study.

Time-dependent bladder tissue regeneration using bilayer bladder acellular matrix graft-silk fibroin scaffolds in a rat bladder augmentation model

With advances in tissue engineering, various synthetic and natural biomaterials have been widely used in tissue regeneration of the urinary bladder in rat models. However, reconstructive procedures remain insufficient due to the lack of appropriate scaffolding, which should provide a waterproof barrier function and support the needs of various cell types. To address these problems, we have developed a bilayer scaffold comprising a porous network (silk fibroin [SF]) and an underlying natural acellular matrix (bladder acellular matrix graft [BAMG]) and evaluated its feasibility and potential for bladder regeneration in a rat bladder augmentation model. Histological (hematoxylin and eosin and Masson's trichrome staining) and immunohistochemical analyses demonstrated that the bilayer BAMG-SF scaffold promoted smooth muscle, blood vessel, and nerve regeneration in a time-dependent manner. At 12weeks after implantation, bladders reconstructed with the BAMG-SF matrix displayed superior structural and functional properties without significant local tissue responses or systemic toxicity. These results demonstrated that the bilayer BAMG-SF scaffold may be a promising scaffold with good biocompatibility for bladder regeneration in the rat bladder augmentation model.

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.