Extracellular Vesicles from Urine-Derived Stem Cell for Tissue Engineering and Regenerative Medicine

The potential of urine-derived stem cells (USCs) for tissue engineering and regenerative medicine has attracted much attention during the last few decades. However, it has been suggested that the effects of the USCs may be endowed by their paracrine extracellular vesicles (EVs) rather than their differentiation. Compared with the USCs, the USC-EVs can cross the barriers more easily and safely, and their inclusions may mediate intercellular communication and promote the tissue repair. This article has summarized the current knowledge and applications about the USC-EVs in tissue engineering and regenerative medicine, and discussed the prospects and challenges for using them as an alternative to cell therapy. Impact statement Urine-derived stem cells (USCs) represent a newly discovered type of stem cells, and studies have proved that the beneficial effects of the USCs may be manifested through their paracrine extracellular vesicles (EVs) rather than through their own differentiation, which opens up new avenues for tissue engineering and regenerative medicine strategies. Therefore, this review aims to summarize the latest research progress and potential clinical applications of the USC-EVs, highlighting the promising potential of the USC-EVs as a therapeutic option in kidney regeneration, genital regeneration, nerve regeneration, bone and cartilage regeneration, and wound healing.

Establishment and comparison of different procedures for modeling intrauterine adhesion in rats: A preliminary study

The establishment of a stable animal model for intrauterine adhesion (IUA) can significantly enhance research on the pathogenesis and pathological changes of this disease, as well as on the development of innovative therapeutic approaches. In this study, three different modeling methods, including phenol mucilage combined mechanical scraping, ethanol combined mechanical scraping and ethanol modeling alone were designed. The morphological characteristics of the models were evaluated. The underlying mechanisms and fertility capacity of the ethanol modeling group were analyzed and compared to those of the sham surgery group. All three methods resulted in severe intrauterine adhesions, with ethanol being identified as a reliable modeling agent and was subsequently subjected to further evaluation. Immunohistochemistry and RT-PCR results indicated that the ethanol modeling group exhibited an increase in the degree of fibrosis and inflammation, as well as a significant reduction in endometrial thickness, gland number, vascularization, and endometrial receptivity, ultimately resulting in the loss of fertility capacity. The aforementioned findings indicate that the intrauterine perfusion of 95 % ethanol is efficacious in inducing the development of intrauterine adhesions in rats. Given its cost-effectiveness, efficacy, and stability in IUA formation, the use of 95 % ethanol intrauterine perfusion may serve as a novel platform for evaluating innovative anti-adhesion materials and bioengineered therapies.

Recent progress in bone-repair strategies in diabetic conditions

Bone regeneration following trauma, tumor resection, infection, or congenital disease is challenging. Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia. It can result in complications affecting multiple systems including the musculoskeletal system. The increased number of diabetes-related fractures poses a great challenge to clinical specialties, particularly orthopedics and dentistry. Various pathological factors underlying DM may directly impair the process of bone regeneration, leading to delayed or even non-union of fractures. This review summarizes the mechanisms by which DM hampers bone regeneration, including immune abnormalities, inflammation, reactive oxygen species (ROS) accumulation, vascular system damage, insulin/insulin-like growth factor (IGF) deficiency, hyperglycemia, and the production of advanced glycation end products (AGEs). Based on published data, it also summarizes bone repair strategies in diabetic conditions, which include immune regulation, inhibition of inflammation, reduction of oxidative stress, promotion of angiogenesis, restoration of stem cell mobilization, and promotion of osteogenic differentiation, in addition to the challenges and future prospects of such approaches.

Multifunctional two-component in-situ hydrogel for esophageal submucosal dissection for mucosa uplift, postoperative wound closure and rapid healing

Endoscopic submucosal dissection (ESD) for gastrointestinal tumors and premalignant lesions needs submucosal fluid cushion (SFC) for mucosal uplift before dissection, and wound care including wound closure and rapid healing postoperatively. Current SFC materials as well as materials and/or methods for post-ESD wound care have single treatment effect and hold corresponding drawbacks, such as easy dispersion, short duration, weak hemostasis and insufficient repair function. Thus, designing materials that can serve as both SFC materials and wound care is highly desired, and remains a challenge. Herein, we report a two-component in-situ hydrogel prepared from maleimide-based oxidized sodium alginate and sulfhydryl carboxymethyl-chitosan, which gelated mainly based on "click" chemistry and Schiff base reaction. The hydrogels showed short gelation time, outstanding tissue adhesion, favorable hemostatic properties, and good biocompatibility. A rat subcutaneous ultrasound model confirmed the ability of suitable mucosal uplift height and durable maintenance time of AM solution. The in vivo/in vitro rabbit liver hemorrhage model demonstrated the effects of hydrogel in rapid hemostasis and prevention of delayed bleeding. The canine esophageal ESD model corroborated that the in-situ hydrogel provided good mucosal uplift and wound closure effects, and significantly accelerated wound healing with accelerating re-epithelization and ECM remodeling post-ESD. The two-component in-situ hydrogels exhibited great potential in gastrointestinal tract ESD.

A Modified Small Intestinal Submucosa Patch with Multifunction to Promote Scarless Repair and Reinvigoration of Urethra

To reconstruct and restore the functions of the male urethra is a challenging task for urologists. The acellular matrix graft currently used in the clinics is mono-functional and may cause a series of complications including stricture, fibrosis, and stone formation. As a result, such graft materials cannot meet the increasing demand for multifunctionality in the field of urethral tissue engineering. In this context, a multifunctional urethral patch is designed for the repair of urethral defects by mixing protocatechualdehyde (PCA) with small intestinal submucosa (SIS) under an alkalin condition to allow cross linking. As shown, the PCA/SIS patch possesses excellent biocompatibility, antioxidant activity, and anti-inflammatory property. More importantly, this patch can remarkably promote the adhesion, proliferation, and directional extension of rabbit bladder epithelial mucous cells (R-EMCs) as well as rabbit bladder smooth muscle cells (R-SMCs), and upregulate the expression of cytokeratin in the EMCs and contractile protein in the SMCs in vitro. In vivo experiments also confirm that the PCA/SIS patch can significantly enhance scarless repair of urethral defects in rabbits by facilitating smooth muscle regeneration, reducing excessive collagen deposition, and accelerating re-epithelialization and neovascularization. Taken together, the newly developed multifunctional PCA/SIS patch provides a promising candidate for urethral regeneration.

Polyphenolic-modified cellulose acetate membrane for bone regeneration through immunomodulation

To enhance the bioactivity of cellulosic derivatives has become an important strategy to promote their value for clinical applications. Herein, protocatechualdehyde (PCA), a polyphenolic molecule, was used to modify a cellulose acetate (CA) membrane by combining with metal ions to confer an immunomodulatory activity. The PCA-modified CA membrane has shown a significant radical scavenging activity, thereby suppressed the inflammatory response and created a favorable immune microenvironment for osteogenesis and mineralization. Moreover, addition of metal ions could further stimulate the osteogenic differentiation of stem cells and accelerate bone regeneration both in vitro and in vivo. This study may provide a strategy to promote the immunomodulatory activity of cellulose-based biomaterials for bone regeneration.

Bioactive ECM-Loaded SIS Generated by the Optimized Decellularization Process Exhibits Skin Wound Healing Ability in Type I Diabetic Rats

Patients with diabetes have 15-25% chance for developing diabetic ulcers as a severe complication and formidable challenge for clinicians. Conventional treatment for diabetic ulcers is to surgically remove the necrotic skin, clean the wound, and cover it with skin flaps. However, skin flap often has a limited efficacy, and its acquisition requires a second surgery, which may bring additional risk for the patient. Skin tissue engineering has brought a new solution for diabetic ulcers. Herein, we have developed a bioactive patch through a compound culture and the optimized decellularization strategy. The patch was prepared from porcine small intestinal submucosa (SIS) and modified by an extracellular matrix (ECM) derived from urine-derived stem cells (USCs), which have low immunogenicity while retaining cytokines for angiogenesis and tissue regeneration. The protocol included the optimization of the decellularization time and the establishment of the methods. Furthermore, the in vitro mechanism of wound healing ability of the patch was investigated, and its feasibility for skin wound healing was assessed through an antishrinkage full-thickness skin defect model in type I diabetic rats. As shown, the patch displayed comparable effectiveness to the USCs-loaded SIS. Our findings suggested that this optimized decellularization protocol may provide a strategy for cell-loaded scaffolds that require the removal of cellular material while retaining sufficient bioactive components in the ECM for further applications.

Application of metabolomics in urolithiasis: the discovery and usage of succinate

Urinary stone is conceptualized as a chronic metabolic disorder punctuated by symptomatic stone events. It has been shown that the occurrence of calcium oxalate monohydrate (COM) during stone formation is regulated by crystal growth modifiers. Although crystallization inhibitors have been recognized as a therapeutic modality for decades, limited progress has been made in the discovery of effective modifiers to intervene with stone disease. In this study, we have used metabolomics technologies, a powerful approach to identify biomarkers by screening the urine components of the dynamic progression in a bladder stone model. By in-depth mining and analysis of metabolomics data, we have screened five differential metabolites. Through density functional theory studies and bulk crystallization, we found that three of them (salicyluric, gentisic acid and succinate) could effectively inhibit nucleation in vitro. We thereby assessed the impact of the inhibitors with an EG-induced rat model for kidney stones. Notably, succinate, a key player in the tricarboxylic acid cycle, could decrease kidney calcium deposition and injury in the model. Transcriptomic analysis further showed that the protective effect of succinate was mainly through anti-inflammation, inhibition of cell adhesion and osteogenic differentiation. These findings indicated that succinate may provide a new therapeutic option for urinary stones.

An Acquired Anterior Glottic Web Model by Heat Injury with a Laryngoscopic Approach in a Rabbit

Acquired anterior glottic webs (AGW) can lead to abnormally elevated phonatory pitch, dysphonia, and airway obstruction requiring urgent intervention. In this study, we construct a novel AGW rabbit model using heat injury by a laryngoscopic way. A primary study was conducted to identify the injury depth in rabbits' vocal folds (VFs) by graded heat energy, and the heat energy for the incurrence of epithelial layer, lamina propria, and muscular layer (ML) injury was 25, 30 and 35 W, respectively. Then, four different models were designed based on the depth and degree of the injury to determine the optimal procedure for AGW formation. Morphological features, vibratory capacity, and histopathologic features of the AGW were correspondingly evaluated. The procedure for conferring the heat injury to the depth of ML and the extent of anterior commissure and middle part of bilateral VFs showed the highest success rate of AGW formation (95%, 19/20). For its low cost, effectiveness, and stability for AGW formation, the heat injury rabbit model with a laryngoscopic approach may provide a new platform for testing novel anti-adhesion materials and bioengineered therapies. Impact Statement Tissue engineering based on biomaterials has been a very hot research field and may be introduced to prevent the acquired anterior glottic web (AGW) formation. However, lacking a widely recognized animal model for AGW has limited the trial of anti-adhesion materials in the larynx. In this study, we have developed a novel rabbit model for AGW formation by conferring a heat injury under a laryngoscope; this model is cheap, effective, and stable for the anti-adhesion materials and bioengineered therapies. Thus, this research would arouse crucial interest and be widely employed.

A self-fused hydrogel for the treatment of glottic insufficiency through outstanding durability, extracellular matrix-inducing bioactivity and function preservation

Injection laryngoplasty with biomaterials is an effective technique to treat glottic insufficiency. However, the inadequate durability, deficient pro-secretion of extracellular matrix (ECM) and poor functional preservation of current biomaterials have yielded an unsatisfactory therapeutic effect. Herein, a self-fusing bioactive hydrogel comprising modified carboxymethyl chitosan and sodium alginate is developed through a dual-crosslinking mechanism (photo-triggered and dynamic covalent bonds). Owing to its characteristic networks, the synergistic effect of the hydrogel for vocal folds (VFs) vibration and phonation is adequately demonstrated. Notably, owing to its inherent bioactivity of polysaccharides, the hydrogel could significantly enhance the secretion of major components (type I/III collagen and elastin) in the lamina propria of the VFs both in vivo and in vitro. In a rabbit model for glottic insufficiency, the optimized hydrogel (C₁A₁) has demonstrated a durability far superior to that of the commercially made hyaluronic acid (HA) Gel. More importantly, owing to the ECM-inducing bioactivity, the physiological functions of the VFs treated with the C₁A₁ hydrogel also outperformed that of the HA Gel, and were similar to those of the normal VFs. Taken together, through a simple-yet-effective strategy, the novel hydrogel has demonstrated outstanding durability, ECM-inducing bioactivity and physiological function preservation, therefore has an appealing clinical value for treating glottic insufficiency.

[Effects and mechanism of human umbilical vein endothelial cells-derived exosomes on wound healing in diabetic rabbits]

Objective: The investigate the effects and mechanism of exosomes derived from human umbilical vein endothelial cells (HUVECs) on wound healing in diabetes rabbits. Methods: The experimental research methods were used. The primary vascular endothelial cells (VECs) and human skin fibroblasts (HSFs) were extracted from skin tissue around ulcer by surgical excision of two patients with diabetic ulcer (the male aged 49 years and the female aged 58 years) admitted to Xiangya Third Hospital of Central South University in June 2019. The cells were successfully identified through morphological observation and flow cytometry. The HUVEC exosomes were extracted by ultracentrifugation and identified successfully by morphological observation, particle size detection, and Western blotting detection. Twenty female 3-month-old New Zealand rabbits were taken to create one type 2 diabetic full-thickness skin defect wound respectively on both sides of the back. The wounds were divided into exosomes group and phosphate buffer solution (PBS) group and treated accordingly, with 20 wounds in each group, the time of complete tissue coverage of wound was recorded. On PID 14, hematoxylin-eosin staining or Masson staining was performed to observe angiogenesis or collagen fiber hyperplasia (n=20). The VECs and HSFs were co-cultured with HUVEC exosomes for 24 h to observe the uptake of HUVEC exosomes by the two kinds of cells. The VECs and HSFs were divided to exosome group treated with HUVEC exosomes and PBS group treated with PBS to detect the cell proliferation on 4 d of culture with cell count kit 8, to detect and calculate the cell migration rate at 24 and 48 h after scratch by scratch test, to detect the cell migration number at 24 h of culture with Transwell test, and to detect the mRNA expressions of nuclear factor-erythroid 2-related factor 2 (NRF2) and transcription activating factor 3 (ATF3) by real time fluorescence quantitative reverse transcription polymerase chain reaction. Besides, the number of vascular branches and vascular length were observed in the tube forming experiment after 12 h of culture of VECs (n=3). The VECs and HSFs were taken and divided into PBS group and exosome group treated as before, and NRF2 interference group, ATF3 interference group, and no-load interference group with corresponding gene interference. The proliferation and migration of the two kinds of cells, and angiogenesis of VECs were detected as before (n=3). Data were statistically analyzed with analysis of variance for repeated measurement, one-way analysis of variance, independent sample t test, and least significant difference test. Results: The time of complete tissue coverage of wound in exosome group was (17.9±1.9) d, which was significantly shorter than (25.2±2.3) d in PBS group (t=4.54, P<0.05). On PID14, the vascular density of wound in PBS group was significantly lower than that in exosome group (t=10.12, P<0.01), and the collagen fiber hyperplasia was less than that in exosome group. After 24 h of culture, HUVEC exosomes were successfully absorbed by VECs and HSFs. The proliferative activity of HSFs and VECs in exosome group was significantly higher than that in PBS group after 4 d of culture (with t values of 54.73 and 7.05, respectively, P<0.01). At 24 and 48 h after scratch, the migration rates of HSFs (with t values of 3.42 and 11.87, respectively, P<0.05 or P<0.01) and VECs (with t values of 21.42 and 5.49, respectively, P<0.05 or P<0.01) in exosome group were significantly higher than those in PBS group. After 24 h of culture, the migration numbers of VECs and HSFs in exosome group were significantly higher than those in PBS group (with t values of 12.31 and 16.78, respectively, P<0.01). After 12 h of culture, the mRNA expressions of NRF2 in HSFs and VECs in exosome group were significantly higher than those in PBS group (with t values of 7.52 and 5.78, respectively, P<0.05 or P<0.01), and the mRNA expressions of ATF3 were significantly lower than those in PBS group (with t values of 13.44 and 8.99, respectively, P<0.01). After 12 h of culture, the number of vascular branches of VECs in exosome group was significantly more than that in PBS group (t=17.60, P<0.01), and the vascular length was significantly longer than that in PBS group (t=77.30, P<0.01). After 4 d of culture, the proliferation activity of HSFs and VECs in NRF2 interference group was significantly lower than that in PBS group and exosome group (P<0.05 or P<0.01); the proliferation activity of HSFs and VECs in ATF3 interference group was significantly higher than that in PBS group (P<0.05 or P<0.01) and significantly lower than that in exosome group (P<0.05 or P<0.01). At 24 and 48 h after scratch, the migration rates of HSFs and VECs in ATF3 interference group were significantly higher than those in PBS group (P<0.05 or P<0.01) and significantly lower than those in exosome group (P<0.05 or P<0.01). At 24 and 48 h after scratch, the migration rates of HSFs and VECs in NRF2 interference group were significantly lower than those in PBS group and exosome group (P<0.05 or P<0.01). After 24 h of culture, the migration numbers of VECs and HSFs in ATF3 interference group were significantly more than those in PBS group (P<0.05) and significantly less than those in exosome group (P<0.05 or P<0.01); the migration numbers of VECs and HSFs in NRF2 interference group were significantly less than those in PBS group and exosome group (P<0.01). After 12 h of culture, the vascular length and number of branches of VECs in NRF2 interference group were significantly decreased compared with those in PBS group and exosome group (P<0.01); the vascular length and number of branches of VECs in ATF3 interference group were significantly increased compared with those in PBS group (P<0.01) and were significantly decreased compared with those in exosome group (P<0.01). Conclusions: HUVEC exosomes can promote the wound healing of diabetic rabbits by promoting the proliferation and migration of VECs and HSFs, and NRF2 and ATF3 are obviously affected by exosomes in this process, which are the possible targets of exosome action.

Single-Step Synthesis of Fe-Fe3 O4 Catalyst for Highly Efficient and Selective Electrochemical Nitrogen Reduction

Nitrogen reduction electrocatalysts are highly attractive for catalytic science. However, most electrocatalysts are limited by their low faradaic efficiency, poor ammonia yield, and tedious and costly catalyst synthesis process. In this work, Fe-based oxide composite nanoparticles with steady chemical states are prepared by a single-step green procedure under ambient conditions. The resulting Fe-Fe₃ O₄ demonstrates remarkable activity and selectivity for nitrogen reduction reaction (NRR) with the highest faradaic efficiency of 53.2±1.8 % and NH₃ yield rate of 24.6±0.8 μg h^-1  mg_cat. ^-1 at -0.4 V (vs. RHE) in 0.1 m Na₂ SO₄ electrolyte. Characterization experiments and theoretical calculation reveal that Fe-Fe₃ O₄ exhibits significantly enhanced charge transfer capability and suppresses the competitive HER process.

Design of biopolymer-based hemostatic material: Starting from molecular structures and forms

Uncontrolled bleeding remains as a leading cause of death in surgical, traumatic, and emergency situations. Management of the hemorrhage and development of hemostatic materials are paramount for patient survival. Owing to their inherent biocompatibility, biodegradability and bioactivity, biopolymers such as polysaccharides and polypeptides have been extensively researched and become a focus for the development of next-generation hemostatic materials. The construction of novel hemostatic materials requires in-depth understanding of the physiological hemostatic process, fundamental hemostatic mechanisms, and the effects of material chemistry/physics. Herein, we have recapitulated the common hemostatic strategies and development status of biopolymer-based hemostatic materials. Furthermore, the hemostatic mechanisms of various molecular structures (components and chemical modifications) are summarized from a microscopic perspective, and the design based on them are introduced. From a macroscopic perspective, the design of various forms of hemostatic materials, e.g., powder, sponge, hydrogel and gauze, is summarized and compared, which may provide an enlightenment for the optimization of hemostat design. It has also highlighted current challenges to the development of biopolymer-based hemostatic materials and proposed future directions in chemistry design, advanced form and clinical application.

•

Biopolymers possess sound biocompatibility, biodegradability and bioactivity for the design of hemostatic materials.

•

Molecular structure designs including component and chemical modification are summarized from a microscopic perspective.

•

Design of various forms of hemostatic materials is discussed and compared synthetically from a macroscopic perspective.

Type H vessels-a bridge connecting subchondral bone remodelling and articular cartilage degeneration in osteoarthritis development

Recent studies have shed light on the cellular and molecular mechanisms that link subchondral bone remodelling and angiogenesis in knee osteoarthritis (KOA). Type H vessels are newly identified bone blood vessel characterized by high expression of CD31 and Endomucin (Emcn) and are coupled with osteogenesis. Factors including mechanical loading, TGF-β1, platelet-derived growth factor type BB (PDGF-BB), the OPG/RANKL/RANK system, osteopontin (OPN), mTOR, VEGF, stromal cell-derived factor l (SDF-1), and prostaglandin E2 (PGE2) participate in the formation of type H vessels in osteoarthritic subchondral bone. In this review, we summarize the current understanding of type H vessels in KOA, as well as the signalling pathways involved and potential therapeutic medicines. In future, the pathogenesis of KOA could be further clarified by the bridge of type H vessels and the design of new disease-modifying osteoarthritis drugs (DMOADs). However, further experiments are needed to determine the upstream signals regulating type H vessel formation in osteoarthritic subchondral bone.

Borderline Developmental Dysplasia of the Hip: A Risk Factor Predicting the Development and Poor Prognosis after Core Decompression for Idiopathic Osteonecrosis of the Femoral Head

OBJECTIVE

It is unclear whether idiopathic osteonecrosis of the femoral head (ONFH) is associated with borderline developmental dysplasia of the hip (BDDH). This study aimed to compare the incidence of BDDH between patients with idiopathic ONFH and matched control subjects and determine the influence of BDDH on poor prognosis after core decompression (CD).

METHODS

We retrospectively examined 78 consecutive patients (111 hips) with idiopathic ONFH undergoing CD and 1:2 matched with 156 control subjects (222 hips). The anteroposterior pelvic radiographs were used to measure the acetabular anatomical parameters and divide included subjects into BDDH or non-BDDH group. The incidence of BDDH and acetabular anatomical parameters were compared between patients with idiopathic ONFH and matched controls. Clinical outcomes, such as Harris Hip Score (HHS), progression of collapse, and conversion to total hip arthroplasty (THA), were compared between patients with BDDH and without BDDH in the idiopathic ONFH group, with a mean follow-up of 72.1 ± 36.6 months.

RESULTS

Patients with idiopathic ONFH had a significantly higher incidence of BDDH than matched controls (29.7% vs 12.2%, p < 0.001). Less acetabular coverage was also found in patients with idiopathic ONFH than in matched controls as demonstrated by lower CEA (28.5° ± 4.7° vs 33.1° ± 5.7°, p < 0.001), AHI (82.4 ± 5.0 vs 86.3 ± 5.4, p < 0.001), ADR (299.6 ± 28.4 vs 318.8 ± 31.3, p < 0.001), and a higher sharp angle (40.0° ± 3.4° vs 37.4° ± 3.7°, p < 0.001). In patients with idiopathic ONFH, the BDDH group had a significantly lower mean HHS at the last follow-up (83.5 ± 17.4 vs 91.6 ± 9.7, p = 0.015) with a different score distribution (p = 0.004), and a lower 5-year survival rate with both clinical failure (66.7%, 95% CI 52.4%-84.9% vs 83.7%, 95% CI 75.2%-93.1%; p = 0.028) and conversion to THA (74.6%, 95% CI 60.7%-91.6% vs 92.1%, 95% CI 85.6%-99.0%; p = 0.008) as the endpoints than the non-BDDH group.

CONCLUSION

The incidence of BDDH was significantly higher in patients with idiopathic ONFH than matched controls, and idiopathic ONFH patients who underwent CD with BDDH had lower mean HHS as well as 5-year survival rate than those without BDDH. Therefore, BDDH should be considered a risk factor predicting the development of idiopathic ONFH as well as poor prognosis after CD.

Application of antibody-conjugated small intestine submucosa to capture urine-derived stem cells for bladder repair in a rabbit model

The need for bladder reconstruction and side effects of cystoplasty have spawned the demand for the development of alternative material substitutes. Biomaterials such as submucosa of small intestine (SIS) have been widely used as patches for bladder repair, but the outcomes are not fully satisfactory. To capture stem cells in situ has been considered as a promising strategy to speed up the process of re-cellularization and functionalization. In this study, we have developed an anti-CD29 antibody-conjugated SIS scaffold (AC-SIS) which is capable of specifically capturing urine-derived stem cells (USCs) in situ for tissue repair and regeneration. The scaffold has exhibited effective capture capacity and sound biocompatibility. In vivo experiment proved that the AC-SIS scaffold could promote rapid endothelium healing and smooth muscle regeneration. The endogenous stem cell capturing scaffolds has thereby provided a new revenue for developing effective and safer bladder patches.

•

We developed an anti-CD29 antibody-crosslinked submucosa of small intestine scaffold (AC-SIS).

•

AC-SIS is capable of specifically capturing urine-derived stem cells (USCs) as well as possesses a sound biocompatibility.

•

AC-SIS promotes in situ tissue regeneration by facilitating the repair of bladder epithelium, smooth muscle and angiogenesis.

•

Design and application of endogenous stem cell capturing scaffolds provides a new strategy for bladder repair.

Human adipose-derived stem cell-loaded small intestinal submucosa as a bioactive wound dressing for the treatment of diabetic wounds in rats

Chronic nonhealing wounds are one of the most common and serious complications of diabetes, which can lead to disability of patients. Adipose-derived stem cells (ADSCs) have emerged as a promising tool for skin wound healing, but the therapeutic potential depends considerably on the cell delivery system. Small intestinal submucosa (SIS) is an extracellular matrix-based membranous scaffold with outstanding repair potential for skin wounds. In this study, we first fabricated a bioactive wound dressing, termed the SIS+ADSCs composite, by using human ADSCs as the seed cell and porcine SIS as the cell delivery vehicle. Then, we systematically investigated, for the first time, the healing potential of this wound dressing in a rat model of type 2 diabetes. In vitro studies revealed that SIS provided a favorable microenvironment for ADSCs and significantly promoted the expression of growth factors critical for chronic wound healing. After implantation in the full-thickness skin wounds of diabetic rats, the SIS+ADSCs composite showed a higher wound healing rate and wound healing quality than those in the PBS, ADSCs, and SIS groups. Along with the ability to modulate the polarization of macrophages in vivo, the SIS+ADSCs composite was potent at promoting wound angiogenesis, reepithelialization, and skin appendage regeneration. Taken together, these results indicate that the SIS+ADSCs composite has good therapeutic potential and high translational value for diabetic wound treatment.

Fabrication and characterization of a pro-angiogenic hydrogel derived from the human placenta

Various hydrogels derived from the xenogeneic extracellular matrix (ECM) have been utilised to promote the repair and reconstruction of numerous tissues; however, there are few studies on hydrogels derived from allogeneic specimens. Human placenta derived hydrogels have been used in the therapy of ischaemic myocardium; however, their physicochemical properties and effects on cellular behaviour remain elusive. As the human placenta retains pro-angiogenic growth factors, it is hypothesized that the placenta hydrogels possess the potential to improve angiogenesis. In this study, a soluble decellularized human placenta matrix generated using a modified method could be stored in a powder form and could be used to form a hydrogel in vitro. Effective decellularization was evaluated by analysing the DNA content and histology images. The placenta hydrogel exhibited a fibrous porous morphology and was injectable. Fourier transform infrared (FTIR) spectroscopy revealed that the placenta hydrogel contained both collagen and sulfated glycosaminoglycans (GAGs). In addition, immunofluorescence imaging and enzyme-linked immunosorbent assay (ELISA) showed that the placenta hydrogel retained pro-angiogenic growth factors, including VEGF and bFGF, and transforming growth factor-β1 (TGF-β1). Further in vitro and in vivo analyses confirmed that the placenta hydrogel exerted better pro-angiogenic effects than a collagen type I hydrogel. Histological data also showed that the placenta hydrogels did not elicit a grave inflammatory response. In conclusion, the results suggest that placenta hydrogels may be deemed an attractive scaffold for regenerative medicine applications, especially in promoting vessel formation.

Exosomes Derived From Human Urine-Derived Stem Cells Overexpressing miR-140-5p Alleviate Knee Osteoarthritis Through Downregulation of VEGFA in a Rat Model

BACKGROUND

Knee osteoarthritis (KOA) is one of the most common chronic musculoskeletal disorders worldwide, for which exosomes derived from stem cells may provide an effective treatment.

PURPOSE

To assess the effect of exosomes derived from human urine-derived stem cells (hUSCs) overexpressing miR-140-5p (miR means microRNA) on KOA in an in vitro interleukin 1β (IL-1β)-induced osteoarthritis (OA) model and an in vivo rat KOA model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Exosomes derived from hUSCs (hUSC-Exos) were isolated and validated. The hUSCs were transfected with miR-140s using lentivirus, and exosomes secreted from such cells (hUSC-140-Exos) were collected. The roles of hUSC-Exos and hUSC-140-Exos in protecting chondrocytes against IL-1β treatment were compared by analyzing the proliferation, migration, apoptosis, and secretion of extracellular matrix (ECM) in chondrocytes. After vascular endothelial growth factor A (VEGFA) was identified as a target of miR-140, the mechanism by which VEGFA can mediate the beneficial effect of miR-140 on OA was investigated using small interfering RNA transfection or chemical drugs. The expression of VEGFA in cartilage and synovial fluid from patients with KOA was measured and compared with that of healthy controls. Surgery for anterior cruciate ligament transection and destabilization of the medial meniscus were performed on the knee joints of Sprague-Dawley rats to establish an animal model of OA, and intra-articular (IA) injection of hUSC-Exos or hUSC-140-Exos was conducted at 4 to 8 weeks after the surgery. Cartilage regeneration and subchondral bone remodeling were evaluated through histological staining and micro-computed tomography analysis.

RESULTS

Proliferation and migration ability were enhanced and apoptosis was inhibited in chondrocytes treated with IL-1β via hUSC-Exos, with the side effect of decreased ECM secretion. hUSC-140-Exos not only retained the advantages of hUSC-Exos but also increased the secretion of ECM by targeting VEGFA, including collagen II and aggrecan. Increased expression of VEGFA during the progression of KOA was also confirmed in cartilage and synovial fluid samples obtained from patients with OA. In the rat OA model, IA injection of hUSC-140-Exos enhanced cartilage regeneration and subchondral bone remodeling.

CONCLUSION

Our results demonstrated the superiority of hUSC-Exos overexpressing miR-140-5p for treating OA compared with the hUSC-Exos. The effect of hUSC-140-Exos for suppressing the progression of KOA is in part mediated by VEGFA.

CLINICAL RELEVANCE

Exosomes derived from stem cells may provide a promising treatment for KOA, and our study can advance the related basic research.

Multi-crosslinking hydrogels with robust bio-adhesion and pro-coagulant activity for first-aid hemostasis and infected wound healing

Bio-adhesive polysaccharide-based hydrogels have attracted much attention in first-aid hemostasis and wound healing for excellent biocompatibility, antibacterial property and pro-healing bioactivity. Yet, the inadequate mechanical properties and bio-adhesion limit their applications. Herein, based on dynamic covalent bonds, photo-triggered covalent bonds and hydrogen bonds, multifunctional bio-adhesive hydrogels comprising modified carboxymethyl chitosan, modified sodium alginate and tannic acid are developed. Multi-crosslinking strategy endows hydrogels with improved strength and flexibility simultaneously. Owing to cohesion enhancement strategy and self-healing ability, considerable bio-adhesion is presented by the hydrogel with a maximal adhesion strength of 162.6 kPa, 12.3-fold that of commercial fibrin glue. Based on bio-adhesion and pro-coagulant activity (e.g., the stimulative aggregation and adhesion of erythrocytes and platelets), the hydrogel reveals superior hemostatic performance in rabbit liver injury model with blood loss of 0.32 g, only 54.2% of that in fibrin glue. The healing efficiency of hydrogel for infected wounds is markedly better than commercial EGF Gel and Ag⁺ Gel due to the enhanced antibacterial and antioxidant properties. Through the multi-crosslinking strategy, the hydrogels show enhanced mechanical properties, fabulous bio-adhesion, superior hemostatic performance and promoting healing ability, thereby have an appealing application value for the first-aid hemostasis and infected wound healing.

•

The multifunctional hydrogel comprising polysaccharides and tannic acid was developed through multi-crosslinking strategy.

•

The multifunctional hydrogel showed 12.3-fold adhesion strength than commercial fibrin glue.

•

The multifunctional hydrogel revealed pro-coagulant activity and excellent hemostatic effect in vivo.

•

The multifunctional hydrogel effectively promoted the healing of infected wounds via multiple mechanisms.

Hypotensive Anesthesia Combined with Tranexamic Acid Reduces Perioperative Blood Loss in Simultaneous Bilateral Total Hip Arthroplasty: A Retrospective Cohort Study

OBJECTIVE

To assess the efficacy and safety of hypotensive anesthesia (HA) combined with tranexamic acid (TXA) for reducing perioperative blood loss in simultaneous bilateral total hip arthroplasty (SBTHA).

METHODS

In this retrospective cohort study, a total of 183 eligible patients (15 females and 168 males, 44.01 ± 9.29 years old) who underwent SBTHA from January 2015 to September 2020 at our medical center were enrolled for analysis. Fifty-nine patients received standard general anesthesia (Std-GA group), the other 85 and 39 patients received HA with an intraoperative mean arterial pressure between 70 and 80 mmHg (70-80 HA group) and below 70 mmHg (<70 HA group), respectively. TXA was administrated to all patients. Perioperative blood loss (total, dominant, and hidden), transfusion rate and volume, hemoglobin and hematocrit reduction, duration of operation and anesthesia, length of hospitalization, range of hip motion as well as postoperative complications were collected from hospital's electronic records and compared between groups.

RESULTS

All patients were followed for more than 3 months. Total blood loss in the two HA groups (1390.25 ± 595.67 ml and 1377.74 ± 423.46 ml, respectively) was significantly reduced compared with that in Std-GA group (1850.83 ± 800.73 ml, P < 0.001). Both dominant and hidden blood loss were dramatically decreased when HA was applied (both P < 0.001). Accordingly, the transfusion rate along with volume in 70-80 HA group (14.1%, 425.00 ± 128.81 ml) and <70 HA group (12.8%, 340.00 ± 134.16 ml) were reduced in comparison with those in Std-GA group (37.3%, 690.91 ± 370.21ml; P = 0.001 and P = 0.014, respectively). The maximal hemoglobin and hematocrit reduction in both HA groups were significantly less than those in Std-GA group (both P < 0.001). Of note, 70-80 and <70 HA groups exhibited comparable efficacy with no significant differences between them. Besides, significant difference in duration of surgery was found among groups (P = 0.044 and P < 0.001), while no differences in anesthesia time and postoperative range of hip motion were observed. Regarding complications, the incidence of both acute kidney injury and postoperative hypotension in <70 HA group was significantly higher than that in 70-80 HA and Std-GA groups (P = 0.014 and P < 0.001). Incidence of acute myocardial injury was similar among groups (P = 0.099) and no other severe complications or mortality were recorded.

CONCLUSION

The combination of HA with a mean arterial pressure (MAP) of 70-80 mmHg and TXA could significantly reduce blood loss and transfusion during SBTHA, in addition to shortening operation time and length of hospitalization, and with no increase in complications.

Urine-Derived Stem Cells for Regenerative Medicine: Basic Biology, Applications, and Challenges

Regenerative medicine based on stem cell research has the potential to provide advanced health care for human beings. Recent studies demonstrate that stem cells in human urine can serve as an excellent source of graft cells for regenerative therapy, mainly due to simple, low-cost, and noninvasive cell isolation. These cells, termed human urine-derived stem cells (USCs), are highly expandable and can differentiate into various cell lineages. They share many biological properties with mesenchymal stem cells, such as potent paracrine effects and immunomodulation ability. The advantage of USCs has motivated researchers to explore their applications in regenerative medicine, including genitourinary regeneration, musculoskeletal repair, skin wound healing, and disease treatment. Although USCs have showed many positive outcomes in preclinical studies, and although the possible applications of USCs for animal therapy have been reported, many issues need to be addressed before clinical translation. This article provides a comprehensive review of USC biology and recent advances in their application for tissue regeneration. Challenges in the clinical translation of USC-based therapy are also discussed. Impact statement Recently, stem cells isolated from urine, referred to as urine-derived stem cells (USCs), have gained much interest in the field of regenerative medicine. Many advantages of human USCs have been found for cell-based therapy: (i) the cell isolation procedure is simple and low cost; (ii) they have remarkable proliferation ability, multidifferentiation potential, and paracrine effects; and (iii) they facilitate tissue regeneration in many animal models. With the hope to facilitate the development of USC-based therapy, we describe the current understanding of USC biology, summarize recent advances in their applications, and discuss future challenges in clinical translation.

Membranous Extracellular Matrix-Based Scaffolds for Skin Wound Healing

Membranous extracellular matrix (ECM)-based scaffolds are one of the most promising biomaterials for skin wound healing, some of which, such as acellular dermal matrix, small intestinal submucosa, and amniotic membrane, have been clinically applied to treat chronic wounds with acceptable outcomes. Nevertheless, the wide clinical applications are always hindered by the poor mechanical properties, the uncontrollable degradation, and other factors after implantation. To highlight the feasible strategies to overcome the limitations, in this review, we first outline the current clinical use of traditional membranous ECM scaffolds for skin wound healing and briefly introduce the possible repair mechanisms; then, we discuss their potential limitations and further summarize recent advances in the scaffold modification and fabrication technologies that have been applied to engineer new ECM-based membranes. With the development of scaffold modification approaches, nanotechnology and material manufacturing techniques, various types of advanced ECM-based membranes have been reported in the literature. Importantly, they possess much better properties for skin wound healing, and would become promising candidates for future clinical translation.

Techniques for increasing the yield of stem cell-derived exosomes: what factors may be involved?

Exosomes are nano-scale extracellular vesicles secreted by cells and constitute an important part in the cell-cell communication. The main contents of the exosomes include proteins, microRNAs, and lipids. The mechanism and safety of stem cell-derived exosomes have rendered them a promising therapeutic strategy for regenerative medicine. Nevertheless, limited yield has restrained full explication of their functions and clinical applications To address this, various attempts have been made to explore the up- and down-stream manipulations in a bid to increase the production of exosomes. This review has recapitulated factors which may influence the yield of stem cell-derived exosomes, including selection and culture of stem cells, isolation and preservation of the exosomes, and development of artificial exosomes.

Minimally invasive transforaminal lumbar interbody fusion versus oblique lateral interbody fusion for lumbar degenerative disease: a meta-analysis

BACKGROUND

Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and oblique lateral interbody fusion (OLIF) are widely used in the treatment of lumbar degenerative diseases. In the present study, a meta-analysis was conducted to compare the clinical and radiographic efficacy of these two procedures.

METHODS

A systematic literature review was performed, and the quality of retrieved studies was evaluated with the Newcastle-Ottawa Scale (NOS). Clinical outcomes, including operation time, intraoperative blood loss, improvement in Visual Analogue Scale (VAS), improvement in Oswestry Disability Index (ODI), Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) effectiveness rate and complications, in addition to radiographic outcomes, including restoration of disc height, disc angle, overall lumbar lordosis, fusion rate and subsidence, were extracted and input into a fixed or random effect model to compare the efficacy of MIS-TLIF and OLIF.

RESULTS

Seven qualified studies were included. Clinically, OLIF resulted in less intraoperative blood loss and shorter operation time than MIS-TLIF. Improvement of VAS for leg pain was more obvious in the OLIF group (P < 0.0001), whereas improvement of VAS for back pain (P = 0.08) and ODI (P = 0.98) as well as JOABPEQ effectiveness rate (P = 0.18) were similar in the two groups. Radiographically, OLIF was more effective in restoring disc height (P = 0.01) and equivalent in improving the disc angle (P = 0.18) and lumbar lordosis (P = 0.48) compared with MIS-TLIF. The fusion rate (P = 0.11) was similar in both groups, while the subsidence was more severe in the MIS-TLIF group (P < 0.00001).

CONCLUSIONS

The above evidence suggests that OLIF is associated with a shorter operation time (with supplementary fixation in the prone position) and less intraoperative blood loss than MIS-TLIF and can lead to better leg pain alleviation, disc height restoration and subsidence resistance. No differences regarding back pain relief, functional recovery, complications, disc angle restoration, lumbar lordosis restoration and fusion rate were found. However, due to the limited number of studies, our results should be confirmed with high-level studies to fully compare the therapeutic efficacy of MIS-TLIF and OLIF.

TRIAL REGISTRATION

PROSPERO ID:  CRD42020201903 .

Observation of rotational coherence in an excited state of CO. Opt Lett 2021;46:3893-3896. [PMID: 34388768 DOI: 10.1364/ol.432315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The vacuum ultraviolet (VUV) radiation is generated in the strong-field-ionized CO molecules through 2+1 resonance excitation with two-color femtosecond laser pulses. When scanning the relative delay between two pump pulses, the rotational-resolved VUV radiations show periodic oscillations lasting as long as 500 ps. Fourier analysis reveals that these oscillations correspond to rotational beat frequencies of the A²Π_i state of CO⁺, which is the result of multi-channel interference during the resonant excitation process. High resolution of Fourier transform spectra up to 0.067cm^-1 allows us to obtain the fine energy levels of the A²Π_i state. The theoretical calculation is in good agreement with the experimental observation. This work reveals the rotational coherence of the ionic excited state and shows the prospect of rotational coherence spectroscopy in measuring fine structures of molecular ions.

Decellularized scaffold and its elicited immune response towards the host: the underlying mechanism and means of immunomodulatory modification

The immune response of the host towards a decellularized scaffold is complex. Not only can a number of immune cells influence this process, but also the characteristics, preparation and modification of the decellularized scaffold can significantly impact this reaction. Such factors can, together or alone, trigger immune cells to polarize towards either a pro-healing or pro-inflammatory direction. In this article, we have comprehensively reviewed factors which may influence the immune response of the host towards a decellularized scaffold, including the source of the biomaterial, biophysical properties or modifications of the scaffolds with bioactive peptides, drugs and cytokines. Furthermore, the underlying mechanism has also been recapitulated.

Procyanidins-crosslinked small intestine submucosa: A bladder patch promotes smooth muscle regeneration and bladder function restoration in a rabbit model

Currently the standard surgical treatment for bladder defects is augmentation cystoplasty with autologous tissues, which has many side effects. Biomaterials such as small intestine submucosa (SIS) can provide an alternative scaffold for the repair as bladder patches. Previous studies have shown that SIS could enhance the capacity and compliance of the bladder, but its application is hindered by issues like limited smooth muscle regeneration and stone formation since the fast degradation and poor mechanical properties of the SIS. Procyanidins (PC), a natural bio-crosslinking agent, has shown anti-calcification, anti-inflammatory and anti-oxidation properties. More importantly, PC and SIS can crosslink through hydrogen bonds, which may endow the material with enhanced mechanical property and stabilized functionalities. In this study, various concentrations of PC-crosslinked SIS (PC-SIS) were prepared to repair the full-thickness bladder defects, with an aim to reduce complications and enhance bladder functions. In vitro assays showed that the crosslinking has conferred the biomaterial with superior mechanical property and anti-calcification property, ability to promote smooth muscle cell adhesion and upregulate functional genes expression. Using a rabbit model with bladder defects, we demonstrated that the PC-SIS scaffold can rapidly promote in situ tissue regrowth and regeneration, in particular smooth muscle remodeling and improvement of urinary functions. The PC-SIS scaffold has therefore provided a promising material for the reconstruction of a functional bladder.

Hydrogel from acellular porcine adipose tissue promotes survival of adipose tissue transplantation

Lipofilling is a popular technique for soft tissue augmentation, limited by unpredictable graft survival. This study aimed at exploring the effect of hydrogel from acellular porcine adipose tissue (HAPA) on angiogenesis and survival of adipose tissue used for lipofilling. The effect of HAPA on adipose-derived stem cells (ADSCs) proliferation, adipogenic differentiation, and vascular endothelial growth factor (VEGF) secretion were evaluated in hypoxia and normoxiain vitro. For thein vivostudy, adipose tissue with phosphate buffered saline, ADSCs, and HAPA (with or without ADSCs) were co-injected subcutaneously into nude mice. HAPA-ADSCs mixture (tissue engineering adipose tissue) was also grafted. Gross observation, volume measurement, and ultrasound observation were assessed. For histological assessment, hematoxylin and eosin, perilipin, cluster of differentiation 31 (CD31), Ki67, and transferase-mediated d-UTP nick end labelling (TUNEL) staining were performed. HAPA improved ADSCs proliferation, VEGF secretion, and adipogenic differentiation under normoxia and hypoxia conditionsin vitrostudy. For thein vivostudy, HAPA showed improved volume retention and angiogenesis, and reduced cell apoptosis when compared to ADSCs-assisted lipofilling and pure lipofilling. In conclusion, HAPA could maintain ADSCs viability and improve cell resistant to hypoxia and might be a promising biomaterial to assist lipofilling.

Adult Stem Cell Therapy for Premature Ovarian Failure: From Bench to Bedside

Premature ovarian failure (POF) is a devastating condition for women of childbearing age with serious health consequences, including distress, infertility, osteoporosis, autoimmune disorders, ischemic heart disease, and increased mortality. In addition to the mainstay estrogen therapy, stem cell therapy has been tested as the result of rapid progress in cell biology and reprogramming research. We hereby provide a review for the latest research and issues related with stem cell-based therapy for POF, and provide a commentary on various methods for enhancing its effect. Large amount of animal studies have demonstrated an extensive benefit of stem cells for failed ovarian recovering. As shown by such studies, stem cell therapy can result in recovery of hormonal levels, follicular activation, ovarian angiogenesis, and functional restoration. Meanwhile, a study of molecular pathways revealed that the function of stem cells mainly depends on their paracrine actions, which can produce multiple factors for the promotion of ovarian angiogenesis and regulation of cellular functions. Nevertheless, studies using disease models also revealed certain drawbacks. Clinical trials have shown that menstrual cycle and even pregnancy may occur in POF patients following transplantation of stem cells, although the limitations, including inadequate number of cases and space for the improvement of transplantation methodology. Only with its safety and effect get substantial improvement through laboratory experiments and clinical trials, can stem cell therapy really bring benefits to more patients. Additionally, effective pretreatment and appropriate transplantation methods for stem cells are also required. Taken together, stem cell therapy has shown a great potential for the reversal of POF and is stepping from bench to bedside. Impact statement Premature ovarian failure (POF) is a devastating condition with serious clinical consequences. The purpose of this review was to summarize the current status of stem cell therapy for POF. Considering the diversity of cell types and functions, a rigorous review is required for the guidance for further research into this field. Meanwhile, the challenges and prospect for clinical application of stem cell treatment, methodological improvements, and innovations are addressed.

Accelerating ESD-induced gastric ulcer healing using a pH-responsive polyurethane/small intestinal submucosa hydrogel delivered by endoscopic catheter

Endoscopic submucosal dissection (ESD) is the standard treatment for early-stage gastric cancer, but the large post-operative ulcers caused by ESD often lead to serious side effects. Post-ESD mucosal repair materials provide a new option for the treatment of post-ESD ulcers. In this study, we developed a polyurethane/small intestinal submucosa (PU/SIS) hydrogel and investigated its efficacy for accelerating ESD-induced ulcer healing in a canine model. PU/SIS hydrogel possessed great biocompatibility and distinctive pH-sensitive swelling properties and protected GES-1 cells from acid attack through forming a dense film in acidic conditions in vitro. Besides, PU/SIS gels present a strong bio-adhesion to gastric tissues under acidic conditions, thus ensuring the retention time of PU/SIS gels in vivo. In a canine model, PU/SIS hydrogel was easily delivered via endoscopy and adhered to the ulcer sites. PU/SIS hydrogel accelerated gastric ulcer healing at an early stage with more epithelium regeneration and slight inflammation. Our findings reveal PU/SIS hydrogel is a promising and attractive candidate for ESD-induced ulcer repair.

Mesenchymal Stem Cells for Chronic Wound Healing: Current Status of Preclinical and Clinical Studies

Healing skin wounds with anatomic and functional integrity, especially under chronic pathological conditions, remain an enormous challenge. Due to their outstanding regenerative potential, mesenchymal stem cells (MSCs) have been explored in many studies to determine the healing ability for difficult-to-treat diseases. In this article, we review current animal studies and clinical trials of MSC-based therapy for chronic wounds, and discuss major challenges that confront future clinical applications. We found that a wealth of animal studies have revealed the versatile roles and the benefits of MSCs for chronic wound healing. MSC treatment results in enhanced angiogenesis, facilitated reepithelialization, improved granulation, and accelerated wound closure. There are some evidences of the transdifferentiation of MSCs into skin cells. However, the healing effect of MSCs depends primarily on their paracrine actions, which alleviate the harsh microenvironment of chronic wounds and regulate local cellular responses. Consistent with the findings of preclinical studies, some clinical trials have shown improved wound healing after transplantation of MSCs in chronic wounds, mainly lower extremity ulcers, pressure sores, and radiation burns. However, there are some limitations in these clinical trials, especially a small number of patients and imperfect methodology. Therefore, to better define the safety and efficiency of MSC-based wound therapy, large-scale controlled multicenter trials are needed in the future. In addition, to build a robust pool of clinical evidence, standardized protocols, especially the cultivation and quality control of MSCs, are recommended. Altogether, based on current data, MSC-based therapy represents a promising treatment option for chronic wounds. Impact statement Chronic wounds persist as a significant health care problem, particularly with increasing number of patients and the lack of efficient treatments. The main goal of this article is to provide an overview of current status of mesenchymal stem cell (MSC)-based therapy for chronic wounds. The roles of MSCs in skin wound healing, as revealed in a large number of animal studies, are detailed. A critical view is made on the clinical application of MSCs for lower extremity ulcers, pressure sores, and radiation burns. Main challenges that confront future clinical applications are discussed, which hopefully contribute to innovations in MSC-based wound treatment.

Hypoxic preconditioning of human urine-derived stem cell-laden small intestinal submucosa enhances wound healing potential

Background

Urine-derived stem cells (USCs) are a valuable stem cell source for tissue engineering because they can be harvested non-invasively. Small intestine submucosa (SIS) has been used as scaffolds for soft tissue repair in the clinic. However, the feasibility and efficacy of a combination of USCs and SIS for skin wound healing has not been reported. In this study, we created a tissue-engineered skin graft, termed the SIS+USC composite, and hypothesized that hypoxic preconditioning would improve its wound healing potential.

Methods

USCs were seeded on SIS membranes to fabricate the SIS+USC composites, which were then cultured in normoxia (21% O₂) or preconditioned in hypoxia (1% O₂) for 24 h, respectively. The viability and morphology of USCs, the expression of genes related to wound angiogenesis and reepithelialization, and the secretion of growth factors were determined in vitro. The wound healing ability of the SIS+USC composites was evaluated in a mouse full-thickness skin wound model.

Results

USCs showed good cell viability and morphology in both normoxia and hypoxic preconditioning groups. In vitro, hypoxic preconditioning enhanced not only the expression of genes related to wound angiogenesis (VEGF and Ang-2) and reepithelialization (bFGF and EGF) but also the secretion of growth factors (VEGF, EGF, and bFGF). In vivo, hypoxic preconditioning significantly improved the wound healing potential of the SIS+USC composites. It enhanced wound angiogenesis at the early stage of wound healing, promoted reepithelialization, and improved the deposition and remodeling of collagen fibers at the late stage of wound healing.

Conclusions

Taken together, this study shows that hypoxic preconditioning provides an easy and efficient strategy to enhance the wound healing potential of the SIS+USC composite.

Copper promotes the migration of bone marrow mesenchymal stem cells via Rnd3-dependent cytoskeleton remodeling

The motility of mesenchymal stem cells (MSCs) is highly related to their homing in vivo, a critical issue in regenerative medicine. Our previous study indicated copper (Cu) might promote the recruitment of endogenous MSCs in canine esophagus defect model. In this study, we investigated the effect of Cu on the motility of bone marrow mesenchymal stem cells (BMSCs) and the underlying mechanism in vitro. Cu supplementation could enhance the motility of BMSCs, and upregulate the expression of hypoxia-inducible factor 1α (Hif1α) at the protein level, and upregulate the expression of rho family GTPase 3 (Rnd3) at messenger RNA and protein level. When Hif1α was silenced by small interfering RNA (siRNA), Cu-induced Rnd3 upregulation was blocked. When Rnd3 was silenced by siRNA, the motility of BMSCs was decreased with or without Cu supplementation, and Cu-induced cytoskeleton remodeling was neutralized. Furthermore, overexpression of Rnd3 also increased the motility of BMSCs and induced cytoskeleton remodeling. Overall, our results demonstrated that Cu enhanced BMSCs migration through, at least in part, cytoskeleton remodeling via Hif1α-dependent upregulation of Rnd3. This study provided an insight into the mechanism of the effect of Cu on the motility of BMSCs, and a theoretical foundation of applying Cu to improve the recruitment of BMSCs in tissue engineering and cytotherapy.

Hydrogel from Acellular Porcine Adipose Tissue Accelerates Wound Healing by Inducing Intradermal Adipocyte Regeneration

As an important component of the skin, intradermal adipocytes are closely associated with skin homeostasis and wound healing. Although studies have focused on the role of fibroblasts, keratinocytes, and inflammatory cells in wound healing, the role of adipocytes has not been fully investigated. Here, we verified whether the induction of adipocyte regeneration in a wound bed can effectively promote wound healing, finding that the hydrogel from acellular porcine adipose tissue in combination with adipose-derived stem cells can induce in situ adipogenesis in the wound microenvironment. The newly regenerated adipocytes enhanced fibroblast migration, accelerated wound closing, and enhanced wound epithelialization. More importantly, newly formed intact skin structure was observed after treating the wound with adipose-derived stem cell-loaded hydrogel from acellular porcine adipose tissue. These results show that hydrogel from acellular porcine adipose tissue might substantially improve re-epithelialization, angiogenesis, and skin-appendage regeneration, making it a promising therapeutic biomaterial for skin wound healing.

Organic composite-mediated surface coating of human acellular bone matrix with strontium

Acellular bone matrix (ACBM) provides an osteoconductive scaffold for bone repair, but its osteoinductivity is poor. Strontium (Sr) improves the osteoinductivity of bone implants. In this study, we developed an organic composite-mediated strontium coating strategy for ACBM scaffolds by using the ion chelating ability of carboxymethyl cellulose (CMC) and the surface adhesion ability of dopamine (DOPA). The organic coating composite, termed the CMC-DOPA-Sr composite, was synthesized under a mild condition, and its chemical structure and strontium ion chelating ability were then determined. After surface decoration, the physicochemical properties of the strontium-coated ACBM (ACBM-Sr) scaffolds were characterized, and their biocompatibility and osteoinductivity were determined in vitro and in vivo. The results showed that the CMC-DOPA-Sr composite facilitated strontium coating on the surface of ACBM scaffolds. The ACBM-Sr scaffolds possessed a sustained strontium ion release profile, exhibited good cytocompatibility, and enhanced the osteogenic differentiation of mesenchymal stem cells in vitro. Furthermore, the ACBM-Sr scaffolds showed good histocompatibility after subcutaneous implantation in nude mice. Taken together, this study provided a simple and mild strategy to realize strontium coating for ACBM scaffolds, which resulted in good biocompatibility and improved osteoinductivity.

Progress in development of bioderived materials for dermal wound healing

Treatment of acute and chronic wounds is one of the primary challenges faced by doctors. Bioderived materials have significant potential clinical value in tissue injury treatment and defect reconstruction. Various strategies, including drug loading, addition of metallic element(s), cross-linking and combining two or more distinct types of materials with complementary features, have been used to synthesize more suitable materials for wound healing. In this review, we describe the recent developments made in the processing of bioderived materials employed for cutaneous wound healing, including newly developed materials such as keratin and soy protein. The focus was on the key properties of the bioderived materials that have shown great promise in improving wound healing, restoration and reconstruction. With their good biocompatibility, nontoxic catabolites, microinflammation characteristics, as well as their ability to induce tissue regeneration and reparation, the bioderived materials have great potential for skin tissue repair.

Biomechanical Analysis of Bilateral Facet Joint Stabilization Using Bioderived Tendon for Posterior Cervical Spine Motion Reservation in Goats

OBJECTIVES

To investigate the biomechanical properties of a novel stabilization method for posterior cervical motion preservation using bioderived freeze-dried tendon.

METHODS

Experiments were conducted both in vitro and in vivo. For the in vitro group, 15 fresh-frozen goat spines (C1-C7) were randomly divided into 3 subgroups: intact (INT-vitro, n = 5), injury model (IM-vitro, n = 5), and bilateral facet joint stabilization (BFJS-vitro, n = 5) subgroups. For the in vivo group, 15 adult goats were randomly divided into 3 experimental subgroups: INT-vivo subgroup (n = 5), IM-vivo subgroup (n = 5), and BFJS-vivo subgroup (n = 5). Goats in the in vivo group were euthanized 12 weeks after surgery. Biomechanical tests were performed to evaluate range of motion. Histologic analysis was conducted to evaluate survival and reactions associated with the bioderived tendon.

RESULTS

Compared with the INT-vitro and INT-vivo subgroups, the flexion of IM-vitro and IM-vivo subgroups increased significantly, respectively (P < 0.05). The flexion of the BFJS-vitro and BFJS-vivo subgroups was significantly smaller than in the IM-vitro and IM-vivo subgroups, respectively (P < 0.05). Significant differences between the BFJS-vitro and BFJS-vivo subgroups were observed in flexion, lateral bending, and rotation (P < 0.05). Histologic evaluation demonstrated that fibers arranged regularly and stained homogeneously. New vessels in growth indicated that the bioderived tendon was survival and processed good regeneration.

CONCLUSIONS

Bilateral facet joint stabilization can significantly limit excessive flexion motion and maintain adequate stability. Furthermore, the preservation of extension motions without limiting lateral bending and rotation ideally simulates the features of the posterior ligamentous complex. This preserves the dynamic stability of the lower cervical spine.

Accelerating effects of genipin-crosslinked small intestinal submucosa for defected gastric mucosa repair

Slow healing of gastric mucosa defects caused by endoscopic surgery is a common but severe clinical problem for lack of an effective treatment. Small intestinal submucosa (SIS) is a bio-derived extracellular matrix scaffold with remarkable repairing ability for soft tissue, but its rapid degradation and poor mechanical properties in the stomach environment limit its application for gastric mucosa regeneration. Herein, we modified SIS by genipin, a natural crosslinking agent, to improve its resistance against degradation in gastric juice and to promote the healing of gastric mucosa defects. The crosslinking characteristics of genipin-crosslinked SIS (GP-CR SIS) were evaluated by crosslinking degree, swelling ratio and FITR, respectively. GP-CR SIS was highly resistant to gastric juice digestion and had a great improvement in mechanical properties. Additionally, GP-CR SIS maintained excellent biocompatibility according to a cytotoxicity test, hemolysis test, and rat subcutaneous implant assay. In an in vivo study, we treated defected gastric mucosa with GP-CR SIS in a rabbit endoscopic submucosal dissection (ESD)-related ulcer model. After two weeks of surgical treatment, GP-CR SIS significantly expedited wound closure and ameliorated newly constructed tissue by providing a protective microenvironment for rapid granulation tissue formation and accelerating angiogenesis/re-epithelialization. In conclusion, this study demonstrates the huge therapeutic potential of GP-CR SIS scaffolds for accelerating defected gastric mucosa regeneration.

Altered gene expression profile in a rat model of gentamicin-induced ototoxicity and nephrotoxicity, and the potential role of upregulated Ifi44 expression

As demonstrated by Alport syndrome, the co-occurrence of auditory and urinary system malformations, and gentamicin-induced ototoxicity and nephrotoxicity, the ears and kidneys potentially share certain molecular pathways. In the present study, microarray chips were used to analyze the changes in the gene expression profile using a rat model of gentamicin-induced ototoxicity and nephrotoxicity, using rat liver tissue as a control. A number of genes were identified to exhibit similar expression changes in the rat ears and kidney tissues, among which microtubule-associated protein 44 (Ifi44), was selected for further analysis to validate its expression changes and confirm potential involvement in the inflammation process in the disease model. Ifi44 is a member of the type I interferon-inducible gene family. Reverse transcription-quantitative polymerase chain reaction, western blotting and immunohistochemistry were performed; the results demonstrated that more inflammatory cells were present in cochlear and renal parenchyma in gentamycin-induced rats, and Ifi44 expression was increased in these two organs compared with control rats. Taken together, with its role in lupus nephritis and expression in the inner ear, the results suggested that Ifi44 is potentially involved in the inflammation associated with gentamicin-induced ototoxicity and nephrotoxicity. The approach of the current study has also provided a strategy for delineating common pathways shared by organs involved in specific diseases.

Hydrogel derived from decellularized porcine adipose tissue as a promising biomaterial for soft tissue augmentation

Decellularized extracellular matrix (ECM) scaffolds from human adipose tissue, characterized by impressive adipogenic induction ability, are promising for soft tissue augmentation. However, scaffolds from autologous human adipose tissue are limited by the availability of tissue resources and the time necessary for scaffold fabrication. The objective of the current study was to investigate the adipogenic properties of hydrogels of decellularized porcine adipose tissue (HDPA). HDPA induced the adipogenic differentiation of human adipose-derived stem cells (ADSCs) in vitro, with significantly increased expression of adipogenic genes. Subcutaneous injection of HDPA in immunocompetent mice induced host-derived adipogenesis without cell seeding, and adipogenesis was significantly enhanced with ADSCs seeding. The newly formed adipocytes were frequently located on the basal side in the non-seeding group, but this trend was not observed in the ADSCs seeding group. Our results indicated that, similar to human adipose tissue, the ECM scaffold derived from porcine adipose tissue could provide an adipogenic microenvironment for adipose tissue regeneration and is a promising biomaterial for soft tissue augmentation. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1756-1764, 2017.

A high speed compact microwave interferometer for density fluctuation measurements in Sino-UNIted Spherical Tokamak

A single-channel 3 mm interferometer has been developed for plasma density diagnostics in the Sino-UNIted Spherical Tokamak (SUNIST). The extremely compact microwave interferometer utilizes one corrugated feed horn antenna for both emitting and receiving the microwave. The beam path lies on the equatorial plane so the system would not suffer from beam path deflection problems due to the symmetry of the cross section. A focusing lens group and an oblique vacuum window are carefully designed to boost the signal to noise ratio, which allows this system to show good performance even with the small-diameter central column itself as a reflector, without a concave mirror. The whole system discards the reference leg for maximum compactness, which is particularly suitable for the small-sized tokamak. An auto-correcting algorithm is developed to calculate the phase evolution, and the result displays good phase stability of the whole system. The intermediate frequency is adjustable and can reach its full potential of 2 MHz for best temporal resolution. Multiple measurements during ohmic discharges proved the interferometer's capability to track typical density fluctuations in SUNIST, which enables this system to be utilized in the study of MHD activities.

Celecoxib and octreotide synergistically ameliorate portal hypertension via inhibition of angiogenesis in cirrhotic rats

Abnormal angiogenesis is critical for portal hypertension in cirrhosis. Except for etiological treatment, no efficient medication or regime has been explored to treat the early stage of cirrhosis when angiogenesis is initiated or overwhelming. In this study, we explored an anti-angiogenesis effort through non-cytotoxic drugs octreotide and celecoxib to treat early stage of cirrhotic portal hypertension in an animal model. Peritoneal injection of thioacetamide (TAA) was employed to induce liver cirrhosis in rats. A combination treatment of celecoxib and octreotide was found to relieve liver fibrosis, portal venous pressure, micro-hepatic arterioportal fistulas, intrahepatic and splanchnic angiogenesis. Celecoxib and octreotide exerted their anti-angiogenesis effect via an axis of cyclooxygenase-2/prostaglandin E2/EP-2/somatostatin receptor-2, which consequently down-regulated phosphorylation of extracellular signal-regulated kinase (p-ERK)–hypoxia-inducible factor-1α (HIF-1α)–vascular endothelial growth factor (VEGF) integrated signaling pathways. In conclusions, combination of celecoxib and octreotide synergistically ameliorated liver fibrosis and portal hypertension of the cirrhotic rats induced by TAA via the inhibition of intrahepatic and extrahepatic angiogenesis. The potential mechanisms behind the regimen may due to the inactivation of p-ERK–HIF-1α–VEGF signaling pathway.

Tissue-engineered ribs for chest wall reconstruction: a case with 12-year follow-up

We hereby report on a case in which a huge chest wall defect generated by resection of a massive aggressive tumor (desmoplastic fibroma) was repaired with osteogenic-induced mesenchymal stem cells embedded in a bone-derived biomaterial. In this case, there were three challenges to overcome: reconstruction of the soft tissue, repair of the skeletal defect of the thoracic wall and repair of the defect in the pleural cavity. The defects of soft tissue and pleural cavity were reconstructed, respectively, with an ipsilateral abdominal flap and a diaphragm muscular flap. The huge defect in the chest wall was successfully repaired with the tissue-engineered ribs, which was confirmed by long-term follow-up with computerized tomography and histological and immunohistochemical evaluations. In view of its effectiveness and safety, tissue-engineered bones may have a broad application for the repair of large skeletal defects and bone regeneration.

Tissue engineered esophagus by copper--small intestinal submucosa graft for esophageal repair in a canine model

Acellular porcine small intestinal submucosa (SIS) has been used for esophagoplasty with success in a canine model. However, it did not lead to complete epithelialization. For better reconstruction, a cellular component is required. Moreover, promotion of angiogenesis with copper has been widely recognized by basic research as well as clinical studies. In this study, we have evaluated the feasibility and effectiveness of combined Cu and SIS (SIS-Cu patch) for the esophageal repair using a canine model. Eighteen male beagle dogs were subjected to surgical resection to produce cervical esophageal defects (5 cm in length, 180° in range). SIS with Cu (5 or 25 μmol L(-1) copper) or without Cu was patched on the esophageal defects. Barium esophagram and histology exam were carried out to evaluate the effectiveness of the therapy. As shown, the SIS-Cu graft promoted re-epithelialization, re-vascularization and muscular regeneration. SIS-Cu patch is more effective than SIS alone for esophageal repair, and the SIS+25 μmol L(-1) Cu group demonstrated additional advantages over the SIS+5 μmol L(-1) Cu.

Tissue engineered esophagus by mesenchymal stem cell seeding for esophageal repair in a canine model

PURPOSE

Acellular porcine small intestinal submucosa (SIS) has been successfully used for esophagoplasty in dogs. However, this has not led to complete epithelialization and muscular regeneration. We undertook the present study to assess the effect of tissue-engineered esophagus generated by seeding bone marrow mesenchymal stem cells (BMSCs) onto an SIS scaffold (BMSCs-SIS) in a canine model.

METHODS

We cultured, passaged, and measured autologous BMSCs and myoblasts with cell proliferation and immunohistochemical assays. We labeled the third passage of BMSCs with PKH-26, a fluorescent dye, before seeded it onto the SIS. We resected canine cervical esophagus to generate a defect 5 cm in length and 50% in circumference, which we repaired with BMSCs-SIS or SIS alone.

RESULTS

Four weeks later, barium esophagram demonstrated that esophageal lumen surface of the patch graft was smoother in the BMSCs-SIS group compared with the SIS group. Histological examination suggested a strong similarity between BMSCs and esophageal myoblasts in terms of morphology and function. Although both BMSCs-SIS and SIS repaired the esophageal defects, we noted complete re-epithelialization with almost no inflammation only in the former group. By 12 wk after the surgery, we observed long bundles of skeletal muscles only in the BMSCs-SIS group, where the microvessel density was also much greater.

CONCLUSIONS

Bone marrow mesenchymal stem cells on an SIS scaffold can promote re-epithelialization, revascularization, and muscular regeneration. This approach may provide an attractive option for esophageal regeneration.