Human adipose-derived mesenchymal stem cells accelerate decellularized neobladder regeneration

Pericardial bioscaffold coated with ECM gels and urothelial cells for the repair of a rabbit urinary bladder defect

Repair of damaged or faulty complex modular organs such as the urinary bladder is a current clinical challenge. The design of constructs for reconstructive urological surgery can draw advantage from the bioactivity of natural extracellular matrix (ECM) bioscaffolds, as well as the activity provided by cells seeded into constructs. Considering these benefits, this work compares the performance of pericardial ECM bioscaffolds and constructs seeded with gel-supported urothelial cells in the repair of urinary bladder defects in rabbits. The bioscaffolds considered in this study are of porcine (pM) and bovine (bM) origin and exhibited a residual composition that confers bioactivity in mesh presentation. Coating an ECM gel on the bioscaffolds promoted the adhesion and viability of urothelial cells. Repairing a full-thickness urinary bladder defect in a rabbit model with the bioscaffolds and constructs resulted in the integration with the host bladder; meanwhile, bladder volumetric capacity was promoted using bM and constructs. Although no contribution of gel/cell seeding to the failure of mechanical properties of the urinary neobladder was observed, this seeding technique is suitable for integration with different strategies to engineer constructs for urinary bladder reconstructive surgery.

Stem cell therapy for bladder regeneration: A comprehensive systematic review

Tissue engineering has been considered a potential choice for urinary system reconstruction. Here, we aim to a broad spectrum of employed stem cells in bladder regeneration by performing a comprehensive systematic review. In January 2024, we searched Scopus, PubMed, and Embase databases for studies that tried bladder regeneration by tissue engineering using stem cells. We excluded non-English studies, review articles, and manuscripts that met the other exclusion criteria. Among 43 included studies, comparative studies demonstrated the similar or superior potentiality of stem cells to regenerate tissues and improve bladder function compared with autologous cells. Furthermore, data suggest an increased use of bio-synthetic scaffolds and their appropriate bio-compatibility with stem cells. The evidence establishes that adipose-derived and bone marrow-derived mesenchymal stem cells are the most frequently used stem cells. And both are suitable for urothelium and smooth muscle formation along with the capability of bone marrow-derived mesenchymal stem cells for lamina propria formation. Additionally, the competency of smooth muscle-derived progenitor cells, urine-derived stem cells, umbilical mesenchymal SCs for smooth muscle and urothelium regeneration, and the capability of hair follicle stem cells for smooth muscle formation are demonstrated. Also, the superiority of endothelial progenitor cells for neo-vascularization and smooth muscle progenitor cells for neuron formation are demonstrated. In addition to adding growth factors to the culturing media, hypoxic conditions and intra-peritoneal incubation are introduced as promoter conditions that can improve histological and physiological components. Available evidence is limited, although it suggests the precious capability of stem cells for bladder regeneration.

The Effect of Adipose-Derived Stem Cell (ADSC)-Exos on the Healing of Autologous Skin Grafts in Miniature Pigs

The skin functions as the body's primary defense barrier; when compromised, it can lead to dehydration, infection, shock, or potentially life-threatening conditions. Miniature pigs exhibit skin characteristics and healing processes highly analogous to humans. Mesenchymal stem cells contribute to skin injury repair through a paracrine mechanism involving exosomes. This research examines whether adipose-derived MSC exosomes effectively enhance healing following autologous skin grafting in miniature pigs. It also compares the roles and distinctions of ADSCs and ADSC-Exos in inflammatory responses and tissue regeneration. This study found significantly reduced levels of oxidative stress products and pro-inflammatory factors, while antioxidant factors, anti-inflammatory factors, and pro-regenerative factors were elevated, and anti-regenerative factor levels decreased. Moreover, the expression levels of key markers-namely, PI3K, Akt, and mTOR-in the regeneration-associated signaling pathway were increased. The alterations in these indicators indicate that ADSC-Exos can regulate inflammatory responses and promote regeneration. This study provides a novel theoretical foundation for the implementation of acellular therapy in clinical settings.

Collagen-based materials in male genitourinary diseases and tissue regeneration

Male genitourinary dysfunction causes serious physical or mental distress, such as infertility and psychological harm, which leads to impaired quality of life. Current conventional treatments involving drug therapy, surgical repair, and tissue grafting have a limited effect on recovering the function and fertility of the genitourinary organs. To address these limitations, various biomaterials have been explored, with collagen-based materials increasingly gaining attention for reconstructing the male genitourinary system due to their superior biocompatibility, biodegradability, low antigenicity, biomimetic 3D matrix characteristics, hemostatic efficacy, and tissue regeneration capabilities. This review covers the recent biomedical applications of collagen-based materials including treatment of erectile dysfunction, premature ejaculation, penile girth enlargement, prostate cancer, Peyronie's disease, chronic kidney disease, etc. Although there are relatively few clinical trials, the promising results of the existing studies on animal models reveal a bright future for collagen-based materials in the treatment of male genitourinary diseases.

Graphic Abstract

A bilayer bioengineered patch with sequential dual-growth factor release to promote vascularization in bladder reconstruction

Bladder tissue engineering holds promise for addressing bladder defects resulting from congenital or acquired bladder diseases. However, inadequate vascularization significantly impacts the survival and function of engineered tissues after transplantation. Herein, a novel bilayer silk fibroin (BSF) scaffold was fabricated with the capability of vascular endothelial growth factor (VEGF) and platelet derived growth factor-BB (PDGF-BB) sequential release. The outer layer of the scaffold was composed of compact SF film with waterproofness to mimic the serosa of the bladder. The inner layer was constructed of porous SF matrix incorporated with SF microspheres (MS) loaded with VEGF and PDGF-BB. We found that the 5% (w/v) MS-incorporated scaffold exhibited a rapid release of VEGF, whereas the 0.2% (w/v) MS-incorporated scaffold demonstrated a slow and sustained release of PDGF-BB. The BSF scaffold exhibited good biocompatibility and promoted endothelial cell migration, tube formation and enhanced endothelial differentiation of adipose derived stem cells (ADSCs) in vitro. The BSF patch was constructed by seeding ADSCs on the BSF scaffold. After in vivo transplantation, not only could the BSF patch facilitate the regeneration of urothelium and smooth muscle, but more importantly, stimulate the regeneration of blood vessels. This study demonstrated that the BSF patch exhibited excellent vascularization capability in bladder reconstruction and offered a viable functional bioengineered patch for future clinical studies.

Research progress of biomaterials and innovative technologies in urinary tissue engineering

Substantial interests have been attracted to multiple bioactive and biomimetic biomaterials in recent decades because of their ability in presenting a structural and functional reconstruction of urinary tissues. Some innovative technologies have also been surging in urinary tissue engineering and urological regeneration by providing insights into the physiological behavior of the urinary system. As such, the hierarchical structure and tissue function of the bladder, urethra, and ureter can be reproduced similarly to the native urinary tissues. This review aims to summarize recent advances in functional biomaterials and biomimetic technologies toward urological reconstruction. Various nanofirous biomaterials derived from decellularized natural tissues, synthetic biopolymers, and hybrid scaffolds were developed with desired microstructure, surface chemistry, and mechanical properties. Some growth factors, drugs, as well as inorganic nanomaterials were also utilized to enhance the biological activity and functionality of scaffolds. Notably, it is emphasized that advanced approaches, such as 3D (bio) printing and organoids, have also been developed to facilitate structural and functional regeneration of the urological system. So in this review, we discussed the fabrication strategies, physiochemical properties, and biofunctional modification of regenerative biomaterials and their potential clinical application of fast-evolving technologies. In addition, future prospective and commercial products are further proposed and discussed.

[Effects and mechanism of annexin A1-overexpressing human adipose-derived mesenchymal stem cells in the treatment of mice with acute respiratory distress syndrome]

Objective: To explore the effects and mechanism of annexin A1 (ANXA1)-overexpressing human adipose-derived mesenchymal stem cells (AMSCs) in the treatment of mice with acute respiratory distress syndrome (ARDS). Methods: The experimental study method was adopted. After the adult AMSCs were identified by flow cytometry, the 3rd passage cells were selected for the follow-up experiments. According to the random number table (the same grouping method below), the cells were divided into ANXA1-overexpressing group transfected with plasmid containing RNA sequences of ANXA1 gene and no-load control group transfected with the corresponding no-load plasmid. The other cells were divided into ANXA1-knockdown group transfected with plasmid containing small interfering RNA sequences of ANXA1 gene and no-load control group transfected with the corresponding no-load plasmid. At post transfection hour (PTH) 72, the fluorescence expression was observed under a fluorescence microscope imaging system, and the protein and mRNA expressions of ANXA1 were detected by Western blotting and real-time fluorescence quantitative reverse transcription polymerase chain reaction respectively (with the sample numbers being 3). Fifty male C57BL/6J mice aged 6-8 weeks were divided into sham injury group, ARDS alone group, normal cell group, ANXA1-overexpressing group, and ANXA1-knockdown group, with 10 mice in each group. Mice in the last 4 groups were treated with endotoxin/lipopolysaccharide to make ARDS lung injury model, and mice in sham injury group were simulated to cause false injury. Immediately after injury, mice in sham injury group and ARDS alone group were injected with normal saline through the tail vein, while mice in normal cell group, ANXA1-overexpressing group, and ANXA1-knockdown group were injected with normal AMSCs, ANXA1-overexpressing AMSCs, and ANXA1-knockdown AMSCs, correspondingly. At post injection hour (PIH) 24, 5 mice in each group were selected, the Evans blue staining was performed to observe the gross staining of the right lung tissue, and the absorbance value of bronchoalveolar lavage fluid (BALF) supernatant of left lung was detected by microplate reader to evaluate the pulmonary vascular permeability. Three days after injection, the remaining 5 mice in each group were taken, the right lung tissue was collected for hematoxylin-eosin staining to observe the pathological changes and immunohistochemical staining to observe the CD11b and F4/80 positive macrophages, and the levels of tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and IL-1β in BALF supernatant of left lung were determined by enzyme-linked immunosorbent assay. Data were statistically analyzed with paired sample t test, one-way analysis of variance, and least significant difference test. Results: At PTH 72, AMSCs in both ANXA1-overexpressing group and ANXA1-knockdown group expressed higher fluorescence intensity than AMSCs in corresponding no-load control group, respectively. At PTH 72, compared with those in corresponding no-load control group, the protein and mRNA expressions of ANXA1 in ANXA1-overexpressing group were significantly increased (wth t values of 249.80 and 6.56, respectively, P<0.05), while the protein and mRNA expressions of ANXA1 in ANXA1-knockdown group were significantly decreased (wth t values of 176.50 and 18.18, respectively, P<0.05). At PIH 24, compared with those in sham injury group (with the absorbance value of BALF supernatant being 0.041±0.009), the lung tissue of mice in ARDS alone group was obviously blue-stained and the absorbance value of BALF supernatant (0.126±0.022) was significantly increased (P<0.05). Compared with those in ARDS alone group, the degree of blue-staining in lung tissue of mice was significantly reduced in normal cell group or ANXA1-overexpressing group, and the absorbance values of BALF supernatant (0.095±0.020 and 0.069±0.015) were significantly decreased (P<0.05), but the degree of blue-staining in lung tissue and the absorbance value of BALF supernatant (0.109±0.016, P>0.05) of mice in ANXA1-knockdown group had no significant change. Compared with that in normal cell group, the absorbance value of BALF supernatant of mice in ANXA1-overexpressing group was significantly decreased (P<0.05). Three days after injection, the lung tissue structure of mice in ARDS alone group was significantly damaged compared with that in sham injury group. Compared with those in ARDS alone group, hemorrhage, infiltration of inflammatory cells, alveolar collapse, and interstitial widening in the lung tissue of mice were significantly alleviated in normal cell group and ANXA1-overexpressing group, while no significant improvement of above-mentioned lung tissue manifestation was observed in ANXA1-knockdown group. Three days after injection, the numbers of CD11b and F4/80 positive macrophages in the lung tissue of mice in ARDS alone group were significantly increased compared with those in sham injury group. Compared with those in ARDS alone group, the numbers of CD11b and F4/80 positive macrophages in lung tissue of mice in normal cell group, ANXA1-overexpressing group, and ANXA1-knockdown group reduced, with the most significant reduction in ANXA1-overexpressing group. Three days after injection, compared with those in sham injury group, the levels of TNF-α, IL-6, and IL-1β in BALF supernatant of mice in ARDS alone group were significantly increased (P<0.05). Compared with those in ARDS alone group, the levels of TNF-α, IL-6, and IL-1β in BALF supernatant of mice in normal cell group and ANXA1-overexpressing group, as well as the level of IL-1β in BALF supernatant of mice in ANXA1-knockdown group were significantly decreased (P<0.05). Compared with that in normal cell group, the level of TNF-α in BALF supernatant of mice was significantly decreased in ANXA1-overexpressing group (P<0.05) but significantly increased in ANXA1-knockdown group (P<0.05). Conclusions: Overexpression of ANXA1 can optimize the efficacy of AMSCs in treating ARDS and enhance the effects of these cells in inhibiting inflammatory response and improving pulmonary vascular permeability, thereby alleviating lung injury of mice with ARDS.

Design strategies for composite matrix and multifunctional polymeric scaffolds with enhanced bioactivity for bone tissue engineering

Over the past few decades, various bioactive material-based scaffolds were investigated and researchers across the globe are actively involved in establishing a potential state-of-the-art for bone tissue engineering applications, wherein several disciplines like clinical medicine, materials science, and biotechnology are involved. The present review article's main aim is to focus on repairing and restoring bone tissue defects by enhancing the bioactivity of fabricated bone tissue scaffolds and providing a suitable microenvironment for the bone cells to fasten the healing process. It deals with the various surface modification strategies and smart composite materials development that are involved in the treatment of bone tissue defects. Orthopaedic researchers and clinicians constantly focus on developing strategies that can naturally imitate not only the bone tissue architecture but also its functional properties to modulate cellular behaviour to facilitate bridging, callus formation and osteogenesis at critical bone defects. This review summarizes the currently available polymeric composite matrices and the methods to improve their bioactivity for bone tissue regeneration effectively.

Therapies Based on Adipose-Derived Stem Cells for Lower Urinary Tract Dysfunction: A Narrative Review

Lower urinary tract dysfunction often requires tissue repair or replacement to restore physiological functions. Current clinical treatments involving autologous tissues or synthetic materials inevitably bring in situ complications and immune rejection. Advances in therapies using stem cells offer new insights into treating lower urinary tract dysfunction. One of the most frequently used stem cell sources is adipose tissue because of its easy access, abundant source, low risk of severe complications, and lack of ethical issues. The regenerative capabilities of adipose-derived stem cells (ASCs) in vivo are primarily orchestrated by their paracrine activities, strong regenerative potential, multi-differentiation potential, and cell–matrix interactions. Moreover, biomaterial scaffolds conjugated with ASCs result in an extremely effective tissue engineering modality for replacing or repairing diseased or damaged tissues. Thus, ASC-based therapy holds promise as having a tremendous impact on reconstructive urology of the lower urinary tract.

[Effects of exosomes from human adipose-derived mesenchymal stem cells on pulmonary vascular endothelial cells injury in septic mice and its mechanism]

Objective: To investigate the effects of exosomes from human adipose-derived mesenchymal stem cells (ADSCs) on pulmonary vascular endothelial cells (PMVECs) injury in septic mice and its mechanism. Methods: The experimental research method was adopted. The primary ADSCs were isolated and cultured from the discarded fresh adipose tissue of 3 patients (female, 10-25 years old), who were admitted to the First Affiliated Hospital of Air Force Medical University undergoing abdominal surgery, and the cell morphology was observed by inverted phase contrast microscope on the 5th day. The expressions of CD29, CD34, CD44, CD45, CD73, and CD90 of ADSCs in the third passage were detected by flow cytometry. The third to the fifth passage of ADSCs were collected, and their exosomes from the cell supernatant were obtained by differential ultracentrifugation, and the shape, particle size, and the protein expressions of CD9, CD63, tumor susceptibility gene 101 (TSG101), and β-actin of exosomes were detected, respectively, by transmission electron microscopy, nano-particle tracking analysis and Western blotting. Twenty-four adult male BALB/c mice were adopted and were divided into normal control group, caecal ligation perforation (CLP) alone group, and CLP+ADSC-exosome group with each group of 8 according to random number table (the same grouping method below) and were treated accordingly. At 24 h after operation, tumor necrosis factor (TNF-α) and interleukin 1β (IL-1β) levels of mice serum were detected by enzyme-linked immunosorbent assay, and lung tissue morphology of mice was detected by hematoxylin-eosin and myeloperoxidase staining, and the expression of 8-hydroxy-deoxyguanosine (8-OHdG) of mouse lung cells was detected by immunofluorescence method. Primary PMVECs were obtained from 1-month-old C57 mice regardless gender by tissue block method. The expression of CD31 of PMVECs was detected by immunofluorescence and flow cytometry. The third passage of PMVECs was co-cultured with ADSCs derived exosomes for 12 h, and the phagocytosis of exosomes by PMVECs was detected by PKH26 kit. The third passage of PMVECs were adopted and were divided into blank control group, macrophage supernatant alone group, and macrophage supernatant+ADSC-exosome group, with 3 wells in each group, which were treated accordingly. After 24 h, the content of reactive oxygen species in cells was detected by flow cytometry, the expression of 8-OHdG in cells was detected by immunofluorescence, and Transwell assay was used to determine the permeability of cell monolayer. The number of samples in above were all 3. Data were statistically analyzed with one-way analysis of variance and least significant difference t test. Results: The primary ADSCs were isolated and cultured to day 5, growing densely in a spindle shape with a typical swirl-like. The percentages of CD29, CD44, CD73 and CD90 positive cells of ADSCs in the third passage were all >90%, and the percentages of CD34 and CD45 positive cells were <5%. Exosomes derived from ADSCs of the third to fifth passages showed a typical double-cavity disc-like structure with an average particle size of 103 nm, and the protein expressions of CD9, CD63 and TSG101 of exosomes were positive, while the protein expression of β-actin of exosomes was negative. At 24 h after operation, compared with those in normal control group, both the levels of TNF-α and IL-1β of mice serum in CLP alone group were significantly increased (with t values of 28.76 and 29.69, respectively, P<0.01); compared with those in CLP alone group, both the content of TNF-α and IL-1β of mice serum in CLP+ADSC-exosome group was significantly decreased (with t values of 9.90 and 4.76, respectively, P<0.05 or P<0.01). At 24 h after surgery, the pulmonary tissue structure of mice in normal control group was clear and complete without inflammatory cell infiltration; compared with those in normal control group, the pulmonary tissue edema and inflammatory cell infiltration of mice in CLP alone group were more obvious; compared with those in CLP alone group, the pulmonary tissue edema and inflammatory cell infiltration of mice in CLP+ADSC-exosome group were significantly reduced. At 24 h after operation, endothelial cells in lung tissues of mice in 3 groups showed positive expression of CD31; compared with that in normal control group, the fluorescence intensity of 8-OHdG positive cells of the lung tissues of mice in CLP alone group was significantly increased, and compared with that in CLP alone group, the fluorescence intensity of 8-OHdG positive cells in the lung tissues of mice in CLP+ADSC-exosome group was significantly decreased. The PMVECs in the 3rd passage showed CD31 positive expression by immunofluorescence, and the result of flow cytometry showed that CD31 positive cells accounted for 99.5%. At 12 h after co-culture, ADSC-derived exosomes were successfully phagocytose by PMVECs and entered its cytoplasm. At 12 h after culture of the third passage of PMVECs, compared with that in blank control group, the fluorescence intensity of reactive oxygen species of PMVECs in macrophage supernatant alone group was significantly increased (t=15.73, P<0.01); compared with that in macrophage supernatant alone group, the fluorescence intensity of reactive oxygen species of PMVECs in macrophage supernatant+ADSC-exosome group was significantly decreased (t=4.72, P<0.01). At 12 h after culture of the third passage of PMVECs, and the 8-OHdG positive fluorescence intensity of PMVECs in macrophage supernatant alone group was significantly increased; and compared with that in blank control group, the 8-OHdG positive fluorescence intensity of PMVECs in macrophage+ADSC-exosome supernatant group was between blank control group and macrophage supernatant alone group. At 12 h after culture of the third passage PMVECs, compared with that in blank control group, the permeability of PMVECs monolayer in macrophage supernatant alone group was significantly increased (t=6.34, P<0.01); compared with that in macrophage supernatant alone group, the permeability of PMVECs monolayer cells in macrophage supernatant+ADSC-exosome group was significantly decreased (t=2.93, P<0.05). Conclusions: Exosomes derived from ADSCs can ameliorate oxidative damage in mouse lung tissue, decrease the level of reactive oxygen species, 8-OHdG expression, and permeability of PMVECs induced by macrophage supernatant.

3D Bioprinting of an In Vitro Model of a Biomimetic Urinary Bladder with a Contract-Release System

The development of curative therapy for bladder dysfunction is usually hampered owing to the lack of reliable ex vivo human models that can mimic the complexity of the human bladder. To overcome this issue, 3D in vitro model systems offering unique opportunities to engineer realistic human tissues/organs have been developed. However, existing in vitro models still cannot entirely reflect the key structural and physiological characteristics of the native human bladder. In this study, we propose an in vitro model of the urinary bladder that can create 3D biomimetic tissue structures and dynamic microenvironments to replicate the smooth muscle functions of an actual human urinary bladder. In other words, the proposed biomimetic model system, developed using a 3D bioprinting approach, can recreate the physiological motion of the urinary bladder by incorporating decellularized extracellular matrix from the bladder tissue and introducing cyclic mechanical stimuli. The results showed that the developed bladder tissue models exhibited high cell viability and proliferation rate and promoted myogenic differentiation potential given dynamic mechanical cues. We envision the developed in vitro bladder mimicry model can serve as a research platform for fundamental studies on human disease modeling and pharmaceutical testing.

Considerations for the clinical use of stem cells in genitourinary regenerative medicine

The genitourinary tract can be affected by several pathologies which require repair or replacement to recover biological functions. Current therapeutic strategies are challenged by a growing shortage of adequate tissues. Therefore, new options must be considered for the treatment of patients, with the use of stem cells (SCs) being attractive. Two different strategies can be derived from stem cell use: Cell therapy and tissue therapy, mainly through tissue engineering. The recent advances using these approaches are described in this review, with a focus on stromal/mesenchymal cells found in adipose tissue. Indeed, the accessibility, high yield at harvest as well as anti-fibrotic, immunomodulatory and proangiogenic properties make adipose-derived stromal/SCs promising alternatives to the therapies currently offered to patients. Finally, an innovative technique allowing tissue reconstruction without exogenous material, the self-assembly approach, will be presented. Despite advances, more studies are needed to translate such approaches from the bench to clinics in urology. For the 21^st century, cell and tissue therapies based on SCs are certainly the future of genitourinary regenerative medicine.

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

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

Urine-based regenerative RNA biomarkers for urinary bladder wound healing

Background: This study aimed to investigate the expression of regeneration-related genes in canine urine during bladder repair. Materials & methods: Canine urine samples were collected after partial cystectomy. Regenerative mRNA of hypoxia-inducible factor (HIF), vascular endothelial growth factor (VEGF), key stem cell transcription factors and cholinergic signals were detected. Results: HIF-1α, VEGF, CD44, IL-6 and prominin-1 expression in canine urine after partial cystectomy exhibited two similar peaks at ∼2 weeks. HIF-1α and VEGF expression were higher in the afternoon than the morning. The expression of key stem cell transcription factors and cholinergic signals also exhibited a rhythm along with bladder healing. Conclusions: The expression of HIF-1α, VEGF, key stem cell transcription factors and cholinergic signals exhibited a time curve distribution during canine bladder healing. The expression trend of some regenerative genes was similar during bladder healing, and a cooperative effect may exist.

Cell-Seeded Acellular Artery for Reconstruction of Long Urethral Defects in a Canine Model

The management of urethral stricture remains a major therapeutic challenge in clinics. Herein, we explored the feasibility of reconstructing a relatively long segment of the urethra by the cell-seeded acellular artery in a canine model. The acellular arterial matrix was obtained from the excised carotid artery of donor dogs. Autologous adipose-derived stem cells (ADSCs) from 6 male dogs were grown and seeded onto the premade acellular arterial matrix. A 3 cm long segment of the urethra was resected in 12 male dogs. Urethroplasty was performed with the acellular arterial matrix seeded with ADSCs in 6 animals and without cells in 6. Serial urethrography was performed at 1 and 3 months postoperatively. Wide urethral calibers without any signs of strictures were confirmed in all 6 animals in the experimental group. In contrast, urethral stricture was demonstrated in 3 animals in the control group. The graft was highly epithelialized and smooth in the experimental group, while graft contracture and scar formation were showed in the control group. Histologic analysis of the cell-seeded arterial matrix at 1 month confirmed the presence of multilayered urothelium and muscle. The levels of tissue formation developed over time with a progressive increase in muscle content. In contrast, extensive fibrosis and sparse smooth muscle were seen in animals treated with matrix without ADSCs. This study provides preclinical evidence that the ADSC-seeded arterial matrix can be used as a tubularized scaffold in the reconstruction of 3 cm long urethral defect in a male canine model. The ADSC-seeded arterial matrix remodels and regenerates normal-appearing urethral tissue layers over time.

Sterilization and disinfection methods for decellularized matrix materials: Review, consideration and proposal

Sterilization is the process of killing all microorganisms, while disinfection is the process of killing or removing all kinds of pathogenic microorganisms except bacterial spores. Biomaterials involved in cell experiments, animal experiments, and clinical applications need to be in the aseptic state, but their physical and chemical properties as well as biological activities can be affected by sterilization or disinfection. Decellularized matrix (dECM) is the low immunogenicity material obtained by removing cells from tissues, which retains many inherent components in tissues such as proteins and proteoglycans. But there are few studies concerning the effects of sterilization or disinfection on dECM, and the systematic introduction of sterilization or disinfection for dECM is even less. Therefore, this review systematically introduces and analyzes the mechanism, advantages, disadvantages, and applications of various sterilization and disinfection methods, discusses the factors influencing the selection of sterilization and disinfection methods, summarizes the sterilization and disinfection methods for various common dECM, and finally proposes a graphical route for selecting an appropriate sterilization or disinfection method for dECM and a technical route for validating the selected method, so as to provide the reference and basis for choosing more appropriate sterilization or disinfection methods of various dECM.

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Asepsis is the prerequisite for the experiment and application of biomaterials.

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Sterilization or disinfection affects physic-chemical properties of biomaterials.

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Mechanism, advantages and disadvantages of sterilization or disinfection methods.

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Factors influencing the selection of sterilization or disinfection methods.

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Selection of sterilization or disinfection methods for decellularized matrix.

Adipose tissue-derived stem cells in breast reconstruction: a brief review on biology and translation

Recent developments in adipose-derived stromal/stem cell (ADSC) biology provide new hopes for tissue engineering and regeneration medicine. Due to their pluripotent activity, paracrine activity, and immunomodulatory function, ADSCs have been widely administrated and exhibited significant therapeutic effects in the treatment for autoimmune disorders, neurodegenerative diseases, and ischemic conditions both in animals and human clinical trials. Cell-assisted lipotransfer (CAL) based on ADSCs has emerged as a promising cell therapy technology and significantly improved the fat graft retention. Initially applied for cosmetic breast and facial enhancement, CAL has found a potential use for breast reconstruction in breast cancer patients. However, more challenges emerge related to CAL including lack of a standardized surgical procedure, the controversy in the effectiveness of CAL, and the potential oncogenic risk of ADSCs in cancer patients. In this review, we summarized the latest research and intended to give an outline involving the biological characteristics of ADSCs as well as the preclinical and clinical application of ADSCs.

Injectable Gel Form of a Decellularized Bladder Induces Adipose-Derived Stem Cell Differentiation into Smooth Muscle Cells In Vitro

Biologic scaffolds composed of extracellular matrix components have been proposed to repair and reconstruct a variety of tissues in clinical and pre-clinical studies. Injectable gels can fill and conform any three-dimensional shape and can be delivered to sites of interest by minimally invasive techniques. In this study, a biological gel was produced from a decellularized porcine urinary bladder by enzymatic digestion with pepsin. The enzymatic digestion was confirmed by visual inspection after dissolution in phosphate-buffered saline solution and Fourier-transform infrared spectroscopy. The rheological and biological properties of the gel were characterized and compared to those of the MatrigelTM chosen as a reference material. The storage modulus G' reached 19.4 ± 3.7 Pa for the 30 mg/mL digested decellularized bladder gels after ca. 3 h at 37 °C. The results show that the gel formed of the porcine urinary bladder favored the spontaneous differentiation of human and rabbit adipose-derived stem cells in vitro into smooth muscle cells to the detriment of cell proliferation. The results support the potential of the developed injectable gel for tissue engineering applications to reconstruct for instance the detrusor muscle part of the human urinary bladder.

Characterization of Crystalline Phase of TiO2 Nanocrystals, Cytotoxicity and Cell Internalization Analysis on Human Adipose Tissue-Derived Mesenchymal Stem Cells

Titanium dioxide (TiO₂) is manufactured worldwide as crystalline and amorphous forms for multiple applications, including tissue engineering, but our study proposes analyzing the impact of crystalline phases of TiO₂ on Mesenchymal Stem Cells (MSCs). Several studies have already described the regenerative potential of MSCs and TiO₂ has been used for bone regeneration. In this study, polydispersity index and sizes of TiO₂ nanocrystals (NCs) were determined. Adipose tissue-derived Mesenchymal Stem Cells (AT-MSCs) were isolated and characterized in order to evaluate cellular viability and the internalization of nanocrystals (NCs). All of the assays were performed using the TiO₂ NCs with 100% anatase (A), 91.6% anatase/9.4% rutile (AR), 64.6% rutile/35.4% anatase (RA), and 84.0% rutile/16% brookite (RB), submitted to several concentrations in 24-h treatments. Cellular localization of TiO₂ NCs in the AT-MSCs was resolved by europium-doped NCs. Viability was significantly improved under the predominance of the rutile phase in NCs with localization restricted at the cytoplasm, suggesting that AR and RA NCs are not genotoxic and can be associated with most cellular activities and metabolic pathways, including glycolysis and cell division.

Synergistic Fabrication of Dose-Response Chitosan/Dextran/β-Glycerophosphate Injectable Hydrogel as Cell Delivery Carrier for Cardiac Healing After Acute Myocardial Infarction

The human mesenchymal stem cells (hMSCs) therapy offering an encouraging the new methods to establish the conveying on the chitosan (C)/dextran (D)/β-glycerophosphate (β-GP) loaded with hMSCs to enhance the acute myocardial infarctions. The synthesized hMSCs-CD@β-GP system displayed the ratio of determination modules, size of the pore, absorbency, and the swellings ratio in the assortment of the 65 ka, 149 ± 39.8 µm, 92.2%, 42 ± 1.38, and 29 ± 1.9, respectively. The fabricated hMSCs-CD@β-GP was highly stable and physicochemical investigated and confirmed the suitability of the materials for cardiac regeneration applications. The in vitro examinations of the injectable hydrogels with hMSCs-CD@β-GP have recognized that the improved survival rate of the cells, increased the pro-inflammatory expressions factors, pro-angiogenic factors analysis confirmed the promising results of the ejection of fractions, fibrosis area, vessel density with decreased infractions size, with suggesting that the remarkable improvement of the heart regenerative function after myocardial infarctions. The new synergistic approach of the injectable hydrogels with hMSCs could able appropriate for the effective treatment of cardiac therapies after acute myocardial infarctions.

Whole Organ Engineering: Approaches, Challenges, and Future Directions

End-stage organ failure remains a leading cause of morbidity and mortality across the globe. The only curative treatment option currently available for patients diagnosed with end-stage organ failure is organ transplantation. However, due to a critical shortage of organs, only a fraction of these patients are able to receive a viable organ transplantation. Those patients fortunate enough to receive a transplant must then be subjected to a lifelong regimen of immunosuppressant drugs. The concept of whole organ engineering offers a promising alternative to organ transplantation that overcomes these limitations. Organ engineering is a discipline that merges developmental biology, anatomy, physiology, and cellular interactions with enabling technologies such as advanced biomaterials and biofabrication to create bioartificial organs that recapitulate native organs in vivo. There have been numerous developments in bioengineering of whole organs over the past two decades. Key technological advancements include (1) methods of whole organ decellularization and recellularization, (2) three-dimensional bioprinting, (3) advanced stem cell technologies, and (4) the ability to genetically modify tissues and cells. These advancements give hope that organ engineering will become a commercial reality in the next decade. In this review article, we describe the foundational principles of whole organ engineering, discuss key technological advances, and provide an overview of current limitations and future directions.