Hydrogel-exosome system in tissue engineering: A promising therapeutic strategy.

Characterized by their pivotal roles in cell-to-cell communication, cell proliferation, and immune regulation during tissue repair, exosomes have emerged as a promising avenue for "cell-free therapy" in clinical applications. Hydrogels, possessing commendable biocompatibility, degradability, adjustability, and physical properties akin to biological tissues, have also found extensive utility in tissue engineering and regenerative repair. The synergistic combination of exosomes and hydrogels holds the potential not only to enhance the efficiency of exosomes but also to collaboratively advance the tissue repair process. This review has summarized the advancements made over the past decade in the research of hydrogel-exosome systems for regenerating various tissues including skin, bone, cartilage, nerves and tendons, with a focus on the methods for encapsulating and releasing exosomes within the hydrogels. It has also critically examined the gaps and limitations in current research, whilst proposed future directions and potential applications of this innovative approach.

Advanced application of carbohydrate-based micro/nanoparticles for rheumatoid arthritis.

Rheumatoid arthritis (RA) is a kind of synovitis and progressive joint destruction disease. Dysregulated immune cell activation, inflammatory cytokine overproduction, and subsequent reactive oxidative species (ROS) production contribute to the RA process. Carbohydrates, including cellulose, chitosan, alginate and dextran, are among the most abundant and important biomolecules in nature and are widely used in biomedicine. Carbohydrate-based micro/nanoparticles(M/NPs) as functional excipients have the ability to improve the bioavailability, solubility and stability of numerous drugs used in RA therapy. For on-demand therapy, smart reactive M/NPs have been developed to respond to a variety of chemical and physical stimuli, including light, temperature, enzymes, pH and ROS, alternating their physical and macroscopic properties, resulting in innovative new drug delivery systems. In particular, advanced products with targeted dextran or hyaluronic acid are exploiting multiple beneficial properties at the same time. In addition to those that respond, there are promising new derivatives in development with microenvironment and chronotherapy effects. In this review, we provide an overview of these recent developments and an outlook on how this class of agents will further shape the landscape of drug delivery for RA treatment.

Effects of Ferroptosis on Cardiovascular Diseases.

Ferroptosis is a novel form of programmed cell death characterized by the accumulation of iron-dependent lipid peroxides, which causes membrane injury. Under the catalysis of iron ions, cells deficient in glutathione peroxidase (GPX4) cannot preserve the balance in lipid oxidative metabolism, and the buildup of reactive oxygen species on the membrane lipids leads to cell death. An increasing body of evidence suggests that ferroptosis plays a significant role in the development and occurrence of cardiovascular diseases. In this paper, we mainly elaborated on the molecular mechanisms regulating ferroptosis and its impact on cardiovascular disease to lay the groundwork for future studies on the prophylaxis and treatment of this patient population.

The Optimal Period of Staged Bilateral Total Knee Arthroplasty Procedures under Enhanced Recovery: A Retrospective Study.

OBJECTIVE: The implications of the interval of staged bilateral total knee arthroplasty (TKA) procedures for postoperative complications and costs are not clear. We aimed to determine the optimal time interval between the two stages of bilateral TKA procedures under the enhanced recovery after surgery (ERAS) protocol. METHODS: This retrospective study of collected data included bilateral TKA cases under the ERAS protocol performed between 2018 and 2021 at the West China Hospital of Sichuan University. The staged time was subdivided into three groups according to the interval between the first TKA and second contralateral TKA: group 1: 2- to 6-month, group 2: 6- to 12-month, and group 3: >12 months. The primary outcome was the incidence of postoperative complications. The secondary outcomes were the length of hospital stay (LOS), hemoglobin (Hb) decrease, hematocrit (Hct) decrease, and albumin (Alb) decrease. RESULTS: We analyzed 281 patients who underwent staged bilateral TKAs between 2018 and 2021 at the West China Hospital of Sichuan University. Regarding postoperative complications, there were no statistically significant differences among the three groups (P = 0.21). For the mean LOS, the 6- to 12-month group had a significantly shorter LOS compared with the 2- to 6-month group (P < 0.01). There was also a significant decrease in Hct of the 2- to 6-month group compared with the 6- to 12-month group and the >12 months group (P = 0.02; P < 0.05, respectively). CONCLUSION: Staging the second arthroplasty for more than a half year seems to offer a reduction in the rate of postoperative complications and LOS under ERAS protocol. ERAS shortens the interval of staged bilateral TKA by at least 6 months for patients who might receive their second surgery without the need to wait for an extended period.

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.

SIGIRR deficiency contributes to CD4 T cell abnormalities by facilitating the IL1/C/EBPß/TNF-α signaling axis in rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is a complex autoimmune disease with multiple etiological factors, among which aberrant memory CD4 T cells activation plays a key role in the initiation and perpetuation of the disease. SIGIRR (single immunoglobulin IL-1R-related receptor), a member of the IL-1 receptor (ILR) family, acts as a negative regulator of ILR and Toll-like receptor (TLR) downstream signaling pathways and inflammation. The aim of this study was to investigate the potential roles of SIGIRR on memory CD4 T cells in RA and the underlying cellular and molecular mechanisms. METHODS: Single-cell transcriptomics and bulk RNA sequencing data were integrated to predict SIGIRR gene distribution on different immune cell types of human PBMCs. Flow cytometry was employed to determine the differential expression of SIGIRR on memory CD4 T cells between the healthy and RA cohorts. A Spearman correlation study was used to determine the relationship between the percentage of SIGIRR+ memory CD4 T cells and RA disease activity. An AIA mouse model (antigen-induced arthritis) and CD4 T cells transfer experiments were performed to investigate the effect of SIGIRR deficiency on the development of arthritis in vivo. Overexpression of SIGIRR in memory CD4 T cells derived from human PBMCs or mouse spleens was utilized to confirm the roles of SIGIRR in the intracellular cytokine production of memory CD4 T cells. Immunoblots and RNA interference were employed to understand the molecular mechanism by which SIGIRR regulates TNF-α production in CD4 T cells. RESULTS: SIGIRR was preferentially distributed by human memory CD4 T cells, as revealed by single-cell RNA sequencing. SIGIRR expression was substantially reduced in RA patient-derived memory CD4 T cells, which was inversely associated with RA disease activity and related to enhanced TNF-α production. SIGIRR-deficient mice were more susceptible to antigen-induced arthritis (AIA), which was attributed to unleashed TNF-α production in memory CD4 T cells, confirmed by decreased TNF-α production resulting from ectopic expression of SIGIRR. Mechanistically, SIGIRR regulates the IL-1/C/EBPß/TNF-α signaling axis, as established by experimental evidence and cis-acting factor bioinformatics analysis. CONCLUSION: Taken together, SIGIRR deficiency in memory CD4 T cells in RA raises the possibility that receptor induction can target key abnormalities in T cells and represents a potentially novel strategy for immunomodulatory therapy.

A Bioactive and Photoresponsive Platform for Wireless Electrical Stimulation to Promote Neurogenesis.

Delivering electrical signals to neural cells and tissue has attracted increasing attention in the treatment of nerve injuries. Unlike traditional wired electrical stimulation, wireless and remote light stimulation provides less invasive and longer-lasting interfaces, holding great promise in the treatment of nerve injuries and neurodegenerative diseases, as well as human-computer interaction. Additionally, a bioactive matrix that bridges the injured gap and induces nerve regeneration is essential for injured nerve repair. However, it is still challenging to construct a 3D biomimetic cell niche with optoelectrical responsiveness. Herein, a bioactive platform for remote and wireless optoelectrical stimulation is established by incorporating hydrophilic poly(3-hexylthiophene) nanoparticles (P3HT NPs) into a biomimetic hydrogel matrix. Moreover, the hydrogel matrix is modified by varying the composition and/or the crosslinking degree to meet the needs of different application scenarios. When exposed to pulsed green light, P3HT NPs in hydrogels convert light signals into electrical signals, resulting in the generation of tens of picoampere photocurrent, which is proved to promote the growth of cortical neurons that covered by hydrogels and the neuronal differentiation of bone marrow mesenchymal stem cells (BMSCs) encapsulated in hydrogels. This work is of great significance for the design of next-generation neural electrodes and scaffolds.

A photoelectric effect integrated scaffold for the wireless regulation of nerve cellular behavior.

Electrical signals are a key factor to promote nerve cell neurogenesis. However, the traditionally used exogenous electrical stimulus mode requires additional equipment and complicated wiring, which is very inconvenient. To date, it has been challenging to provide electrical signals to nerve cells in a non-invasive and wireless controllable way, accompanied by the construction of a biomimetic cell microenvironment for supporting nerve cell survival and functional expression. Herein, a new concept of a light-powered oriented bioactive scaffold for remote and wireless electrical stimulation has been developed. By combining electrospinning and electrospraying, the highly oriented polycaprolactone (PCL) microfibrous scaffold with co-sprayed bioactive collagen and photoelectric poly-3-hexylthiophene nanoparticles (P3HT NPs) was obtained, named as PCL-P3HT-Col, which exhibits a considerable photoelectric effect and vital characteristics of the native nerve extracellular matrix. The results show that a photocurrent ranging from 20-80 pA was obtained by changing the light density of a 530 nm green light source. Further, the specific photoelectric conversion effect trigged by the P3HT NPs promotes the oriented elongation and up-regulation of neuronal characteristic factors in rat pheochromocytoma cells (PC12 cells), which is controlled by L-type voltage-gated calcium channel (L-VGCC) activity. This study provides new insights to engineer self-powered scaffolds towards the non-invasive and wireless-controlled stimulation mode of a variety of cells and tissues.

Saikosaponin D Alleviates DOX-induced Cardiac Injury In Vivo and In Vitro.

ABSTRACT: As a highly efficient anticancer agent, doxorubicin (DOX) is used for treatment of various cancers, but DOX-induced oxidative damages contribute to a degenerative irreversible cardiac toxicity. Saikosaponin D (SSD), which is a triterpenoid saponin with many biological activities including anti-inflammatory effects and antioxidant properties, provides protection against pathologic cardiac remodeling and fibrosis. In the present study, we investigated the work of SSD for DOX-induced cardiotoxicity and the involved mechanisms. We observed that DOX injection induced cardiac injury and malfunction and decreased survival rate. Besides, DOX treatment increased lactate dehydrogenase leakage, cardiomyocyte apoptosis, and myocardium fibrosis and decreased the size of cardiomyocytes. Meanwhile, all the effects were notably attenuated by SSD treatment. In vitro, we found that 1 µM SSD could enhance the proliferation of H9c2 cells and inhibit DOX-induced apoptosis. It was found that the levels of malondialdehyde (MDA) and reactive oxygen species were significantly reduced by improving the activities of the endogenous antioxidative enzymes including catalase and glutathione peroxidase. Furthermore, SSD treatment could downregulate the DOX-induced p38 phosphorylation. Our results suggested that SSD efficiently protected the cardiomyocytes from DOX-induced cardiotoxicity by inhibiting the excessive oxidative stress via p38-MAPK (mitogen-activated protein kinase, MAPK) signaling pathway.

Vinculin orchestrates prostate cancer progression by regulating tumor cell invasion, migration, and proliferation.

BACKGROUND: Prostate cancer (PCa) is a leading cause of death in men, and effective treatment of PCa requires further development. Our study aimed to investigate the potential role of vinculin (VCL) in PCa progression in vitro and in vivo. METHODS: We investigated the methylation level of the VCL promoter based on the TCGA database. The knockdown efficacy of VCL gene expression was confirmed by quantitative polymerase chain reaction, Western blot analysis, and immunofluorescence. Furthermore, morphological changes in PCa cells were detected using phalloidin staining. The mobility of PCa cells was measured using transwell assays and high-content analysis. Moreover, cell growth and viability were determined using the colony formation and cell counting kit-8 assays. The role of VCL in tumor growth in vivo was investigated using a subcutaneous xenograft model generated by injecting tumor cells into the right flank of BALB/c nude mice. RESULTS: The methylation level of the VCL promoter in PCa was significantly downregulated concomitant with age and the progression of nodal metastasis. VCL expression was markedly decreased by shRNA. Importantly, VCL knockdown significantly changed the cell morphology; inhibited the migration, invasion, and movement; and repressed colony formation and viability of PCa cells in vitro. Furthermore, downregulation of VCL suppressed tumor growth in vivo. CONCLUSIONS: Our study comprehensively evaluated the role of VCL in PCa progression in vivo and in vitro. The findings of the present study suggest that VCL can be a potential target for PCa prognosis and treatment.

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.

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.

Identification and characterization of two morphologically distinct stem cell subpopulations from human urine samples.

Urine-derived stem cells (USCs) have shown potentials for the treatment of skeletal and urological disorders. Based on published literature and our own data, USCs consist of heterogeneous populations of cells. In this paper, we identify and characterize two morphologically distinct subpopulations of USCs from human urine samples, named as spindle-shaped USCs (SS-USCs) and rice-shaped USCs (RS-USCs) respectively. The two subpopulations showed similar clone-forming efficiency, while SS-USCs featured faster proliferation, higher motility, and greater potential for osteogenic and adipogenic differentiation, RS-USCs showed greater potential for chondrogenic differentiation. POU5F1 was strongly expressed in both subpopulations, but MYC was weakly expressed. Both subpopulations showed similar patterns of CD24, CD29, CD34, CD44, CD73, CD90 and CD105 expression, while a higher percentage of RS-USCs were positive for CD133. SS-USCs were positive for VIM, weakly positive for SLC12A1 and UMOD, and negative for KRT18, NPHS1, AQP1 and AQP2, indicating a renal mesenchyme origin; while RS-USCs are positive for VIM, partially positive for KRT18, NPHS1, AQP1, SLC12A1 and UMOD, and negative for AQP2, indicating a nephron tubule origin. The above results can facilitate understanding of the biological characteristics of subpopulations of USCs, and provide a basis for further research and applications of such cells.

Collagen Hydrogel Functionalized with Collagen-Targeting IFNA2b Shows Apoptotic Activity in Nude Mice with Xenografted Tumors.

Interferon alpha 2b (IFNA2b) has been used in immunotherapy for cancers with certain success. To reduce fast diffusion of IFNA2b and consequent dose-dependent side effects, we constructed a collagen hydrogel loaded with IFNA2b fused to collagen-binding domain by using methods of tissue engineering. The fusion protein showed apoptotic activity similar to that of native IFNA2b against MCF-7 cells in vitro, but with relatively higher affinity for collagen type I. Accordingly, the former diffused out of the collagen matrix slower than the latter. Importantly, collagen hydrogels loaded with the fusion protein possessed apoptotic activity in vitro and released the engineered cytokine in a controlled manner. In addition, such hydrogels reduced tumor size and extended the survival of the mouse model with xenografted tumors, which suggested a moderate antitumor activity in vivo.

Nanostructured titanium surfaces fabricated by hydrothermal method: Influence of alkali conditions on the osteogenic performance of implants.

Hydrothermal method is an easy-to-use approach for creating nanostructured surfaces on titanium (Ti). However, whether the alkali conditions of this method influence the osteogenic potential of the modified surfaces remains unknown. In this study, we fabricated nanostructured surfaces, termed the Ti-1, Ti-5, and Ti-10 groups, by using the hydrothermal method in 1 M, 5 M, and 10 M NaOH aqueous solutions, respectively. An untreated Ti surface served as a control. The osteogenic performance of modified surfaces was systemically investigated, including the proliferation and osteogenic differentiation of human osteoblast-like MG63 cells in vitro and the osteointegration of implants in a rabbit femoral condyle defect model. After hydrothermal treatment, the hydrophilicity of modified surfaces was greatly enhanced. The Ti-1 group showed a nanowire-like topography, while the Ti-5 and Ti-10 groups exhibited a nanopetal-like topography with different pore sizes. Compared with the untreated Ti surface, the modified surfaces showed good cytocompatibility and enhanced the osteogenic differentiation of MG-63 cells. Compared with the other modified surfaces, the Ti-5 group was the most favourable for the osteogenic differentiation of cells, showing higher levels of alkaline phosphatase activity, osteogenic gene expression, mineralization and osteoprotegerin secretion. Twelve weeks after implantation at the bone defects, the Ti-5 group showed superior peri-implant bone regeneration and higher peak push-out force than the other groups. Overall, this study revealed the crucial role of alkali conditions of hydrothermal method in modulating the material characteristics of modified surfaces and their osteogenic performance in vitro and in vivo, highlighting the need for optimizing the processing conditions of hydrothermal method for enhanced osteointegration.

Comparison of small intestinal submucosa and polypropylene mesh for abdominal wall defect repair.

Abdominal wall defects are a common medical problem, and inadequate repair methods can lead to serious complications. Abdominal wall reconstruction using autologous tissue, or non-biological, biological, or composite patches is often performed to repair defective areas. In particular, composite patches containing both polymeric and biological materials have gained increasing attention due to their good mechanical properties and biocompatibility. However, it is still unclear whether the quality of repairs using composite patches is superior to that of a biological patch. Based on the limitations of previous studies, we compared small intestinal submucosa (SIS) patches with SIS + polypropylene mesh (PPM) patches for repairing abdominal wall defects in adult beagle dogs. Forty-five female dogs were subjected to surgical resection to produce abdominal wall defects. SIS or SIS + PPM was used as patch for the defects. Morphology, biomechanics, and histological evaluations were performed to evaluate the efficacy and safety of such therapies. Our findings demonstrated that SIS had advantages over SIS + PPM considering biological activity and histocompatibility without increasing the risk of repair failure.

[EFFECT OF HUMAN PLACENTAL DECIDUA BASALIS DERIVED MESENCHYMAL STEM CELLS IN REPAIR OF NUDE MICE SKIN WOUND].

OBJECTIVE: To investigate the effectiveness of human placental decidua basalis derived mesenchymal stem cells (PDB-MSCs) in repairing full-thickness skin defect of nude mice. METHODS: Human placenta samples were obtained from healthy donor mothers with written informed consent. PDB-MSCs were isolated through enzymic digestion and density gradient centrifugation; the 4th passage cells were identified by cellular morphology, cell adipogenic and osteogenic differentiation, and phenotype evaluation. Forty-two 4-5-week-old BALB/c female nude mice were randomly divided into experimental group (n=21) and control group (n=21). The 4th passage PDB-MSCs solution (200 µL, 5×106/mL) was injected into the mice of experimental group via caudal vein; the mice of control group were given equal volume of PBS. The full-thickness skin defect model of 1.5 cm×1.5 cm in size was made after 3 days. The wound healing was observed generally at 1, 2, 4, 7, 14, 18, 21, 25, and 30 days after operation, and the wound healing rate was calculated after wound decrustation. HE staining was used to observe the wound repair at 1, 7, 14, 21, and 31 days; immunofluorescent staining was used for cellular localization at 7, 14, and 31 days after operation. RESULTS: Cells isolated from human placenta were MSCs which had multipotential differentiation ability and expressed MSCs phenotype. Animals survived to the end of the experiment. The general observation showed that the experimental group had a faster skin repairing speed than the control group; the time for decrustation was 12-14 days in experimental group and was 14-17 days after operation in the control group. The wound healing rate of experimental group was significantly higher than that of control group at 14, 18, and 21 days (t=4.001, P=0.016; t=3.380, P=0.028; t=3.888, P=0.018), but no significance was found at 25 and 30 days (t=1.565, P=0.193; t=1.000, P=0.423). HE staining showed lower inflammatory reaction, and better regeneration of the whole skin and glands with time in the experimental group. The immunofluorescent staining was positive in skin defect area of experimental group at different time points which displayed that human PDB-MSCs existed. CONCLUSIONS: Through enzymic digestion and density gradient centrifugation, PDB-MSCs can be obtained. Pre-stored PDB-MSCs can mobilize to the defect area and participate in repair of nude mice skin.

Characteristics of mesenchymal stem cells isolated from bone marrow of giant panda.

In present study, we report on bone marrow (BM) mesenchymal stem cells (MSCs) that are isolated from giant pandas. Cells were collected from the BM of two stillborn giant pandas. The cells were cultured and expanded in 10% fetal bovine serum medium. Cell morphology was observed under an inverted microscopy, and the proliferation potential of the cells was evaluated by counting cell numbers for eight consecutive days. Differentiation potentials of the cells were determined by using a variety of differentiation protocols for osteocytes, adipocytes, neuron cells, and cardiomyocytes. Meanwhile, the specific gene expressions for MSCs or differentiated cells were analyzed by RT-PCR. The isolated cells exhibited a fibroblast-like morphology; expressed mesenchymal specific markers such as cluster of differentiation 73 (CD73), SRY (sex determining region Y)-box 2 (SOX-2), guanine nucleotide-binding protein-like 3 (GNL3), and stem cell factor receptor (SCFR); and could be differentiated into osteocytes and adipocytes that were characterized by Alizarin Red and Oil Red O staining. Under appropriate induction conditions, these cells were also able to differentiate into neuroglial-like or myocardial-like cells that expressed specific myocardial markers such as GATA transcription factors 4 (GATA-4), cardiac troponin T (cTnT), and myosin heavy chain 7B (MYH7B), or neural specific markers such as Nestin and glial fibrillary acidic protein (GFAP). This study demonstrated stem cells recovery and growth from giant pandas. The findings suggest that cells isolated from the BM of giant pandas have a high proliferative capacity and multiple differentiation potential in vitro which might aid conservation efforts.

An experimental study of the pathogenicity of a duck hepatitis A virus genotype C isolate in specific pathogen free ducklings.

Duck hepatitis A virus genotype C (DHAV-C), recognized recently, is one of the pathogens causing fatal duck viral hepatitis in ducklings, especially in Asia. To demonstrate the pathogenesis of the DHAV-C isolate, 3-day-old specific pathogen free ducklings were inoculated subcutaneously with a DHAV-C isolate and the clinical signs were observed. Virus distribution, histological and apoptotic morphological changes of various tissues were examined at different times post inoculation. The serial, characteristic changes included haemorrhage and swelling of the liver. Apoptotic cells and virus antigen staining were found in all of the tissues examined. Where more virus antigen staining was detected, there were more severe histopathological and apoptotic changes. The amount of virus antigen and the histological and apoptotic morphological changes agreed with each other and became increasingly severe with length of time after infection. Apoptotic cells were ubiquitously distributed, especially among lymphocytes, macrophages and monocytes in immune organs such as the bursa of Fabricius, thymus and spleen, and in liver, kidney and cerebral cells. Necrosis was also observed within 72 h post inoculation in all organs examined, except the cerebrum, and was characterized by cell swelling and collapsed plasma membrane. These results suggest that the recent outbreak of disease caused by DHAV-C virus is pantropic, causing apoptosis and necrosis of different organs. The apoptosis and necrosis caused by the DHAV-C field strain in this study is associated with pathogenesis and DHAV-C-induced lesions.