General requirements for the production of extracellular vesicles derived from human stem cells.

'General requirements for the production of extracellular vesicles derived from human stem cells' is the first guideline for stem cells derived extracellular vesicles in China, jointly drafted and agreed upon by experts from the Chinese Society for Stem Cell Research. This standard specifies the general requirements, process requirements, packaging and labelling requirements and storage requirements for preparing extracellular vesicles derived from human stem cells, which is applicable to the research and production of extracellular vesicles derived from stem cells. It was originally released by the China Society for Cell Biology on 30 August 2022. We hope that the publication of this guideline will promote institutional establishment, acceptance and execution of proper protocols, and accelerate the international standardisation of extracellular vesicles derived from human stem cells.

GMP-grade microcarrier and automated closed industrial scale cell production platform for culture of MSCs.

Efficient and large-scale expansion of mesenchymal stem/stromal cells (MSCs) has always been a formidable challenge to researchers in cell-based therapies and regenerative medicine. To reconcile major drawbacks of 2D planar culturing system, we innovatively developed an automated closed industrial scale cell production (ACISCP) platform based on GMP-grade microcarrier for culture of umbilical cord-mesenchymal stem/stromal cells (UCMSCs), in accordance with the criteria of stem cell bank. ACISCP system is a fully closed system, which employs different models of vivaSPIN bioreactors (CytoNiche Biotech, China) for scale-up cell culture and vivaPREP (CytoNiche Biotech, China) for automated cell harvesting and cell dosage preparation. To realize industrial scale expansion of UCMSCs, a three-stage expansion was conducted with 1 L, 5 and 15 L vivaSPIN bioreactors. Using 3D TableTrix® and ACISCP system, we inoculated 1.5 × 107 of UCMSCs into 1 L vivaSPIN bioreactor and finally scaled to two 15 L bioreactor. A final yield of 2.09 × 1010 cells with an overall expansion factor of 1975 within 13 days. The cells were harvested, concentrated, washed and prepared automatically with vivaPREP. The entire process was realized with ACISCP platform and was totally enclosed. Critical quality attributes (CQA) assessments and release tests of MSCs, including sterility, safety, purity, viability, identity, stability and potency were performed accordingly. The quality of cells harvested from 3D culture on the ACISCP and conventional 2D planar culture counterpart has no significant difference. This study provides a bioprocess engineering platform, harnessing GMP-grade 3D TableTrix® microcarriers and ACISCP to achieve industrial-scale manufacturing of clinical-grade hMSCs.

Requirments for primary human hepatocyte.

'Requirements for Primary Human Hepatocyte' is the first set of guidelines on Primary Human Hepatocyte in China, jointly drafted and agreed upon by experts from the Chinese Society for Stem Cell Research. This standard specifies the technical requirements, test methods, test regulations, instructions for use, labelling requirements, packaging requirements, storage requirements and transportation requirements for Primary Human Hepatocyte, which is applicable to the quality control for Primary Human Hepatocyte. It was originally released by the China Society for Cell Biology on 9 January 2021. We hope that publication of these guidelines will promote institutional establishment, acceptance and execution of proper protocols and accelerate the international standardization of Primary Human Hepatocyte for applications.

Human mesenchymal stem cells.

Mesenchymal stem cells (MSCs) have attracted great interest for cell therapy and tissue regeneration due to their self-renewal capacity, multipotency and potent immunomodulatory effects on immune cells. However, heterogeneity of MSCs has become a prominent obstacle to limit their translation into practice, as cells from different tissue sources or each individual have great differences in their transcriptomic signatures, differentiation potential and biological functions. Therefore, there is an urgent need for consensus standard for the quality control and technical specifications of MSCs. 'Human Mesenchymal Stem Cells' is the latest set of guidelines on hMSC in China, jointly drafted and agreed upon by experts from the Chinese Society for Stem Cell Research. This standard specifies the technical requirements, test methods, test regulations, instructions for use, labelling requirements, packaging requirements, storage requirements, transportation requirements and waste disposal requirements for hMSC, which is applicable to the quality control for hMSC. It was originally released by the China Society for Cell Biology on 9 January 2021. We hope that publication of these guidelines will facilitate institutional establishment, acceptance and execution of proper protocols, and accelerate the international standardization of hMSC for clinical development and therapeutic applications.

Mesenchymal stem cells modified by FGF21 and GLP1 ameliorate lipid metabolism while reducing blood glucose in type 2 diabetic mice.

OBJECTIVE: The purpose of this study was to investigate the therapeutic effects of genetically modified mesenchymal stem cells (MSCs) in the treatment of type 2 diabetes mellitus (T2DM) in order to identify a new method for treating diabetes that differs from traditional medicine and to provide a new means by which to fundamentally improve or treat diabetes. METHODS: MSCs derived from adipose tissue were modified to overexpress FGF21 and GLP1, which was achieved through lentiviral particle transduction. The cells were transplanted into BKS.Cg-Dock7m+/+Leprdb/Nju mice (T2DM mouse model). Injections of physiological saline (0.1 mL) and liraglutide (0.5 mg/kg) were used as negative and positive controls, respectively. ELISA or Western blotting was used for protein analysis, and quantitative real-time PCR was used for gene expression analysis. RESULTS: Genetic modification had no effects on the morphology, differentiation ability, or immunophenotype of MSCs. Moreover, MSC-FGF21+GLP1 cells exhibited significantly increased secretion of FGF21 and GLP1. In the T2DM mouse model, the transplantation of MSC-FGF21+GLP1 cells ameliorated the changes in blood glucose and weight, promoted the secretion of insulin, enhanced the recovery of liver structures, and improved the profiles of lipids. Moreover, FGF21 and GLP1 exerted synergistic effects in the regulation of glucolipid metabolism by controlling the expression of insulin, srebp1, and srebp2. CONCLUSION: Stem cell treatment based on MSCs modified to overexpress the FGF21 and GLP1 genes is an effective approach for the treatment of T2DM.

Suppression of OCT2/MRP2 decreases kidney injury and enhances the chemosensitivity of co-administration of cisplatin and astragaloside IV / 药学学报

Kidney injury and decreased chemosensitivity of tumor cells are obstacles with cisplatin (CDDP) chemotherapy. Down-regulation of the organic cation transporter 2 (OCT2) and multidrug resistance-associated protein 2 (MRP2) is a key means to alleviate CDDP-induced kidney injury and increase chemosensitivity. Astragaloside IV (AS IV) is obtained from the well-known traditional Chinese herb Astragalus membranaceus. This study explored the role of AS IV in preventing kidney injury and enhancing the antitumor effect of CDDP by suppressing OCT2 expression in kidney and MRP2 in tumors. This project was reviewed and approved by the Animal Ethics Committee of the First Hospital of Jilin University. The effects of AS IV on CDDP inhibition of tumor growth and promotion of apoptosis were assessed in Lewis lung tumor (LLC)-bearing mice by H&E and TUNEL staining. Kidney injury was assessed by serum biochemical parameters and H&E staining. We used Western blotting and immunohistochemistry assays to detect OCT2 and MRP2 expression in kidney and tumor. The concentration of CDDP in kidney and tumor was measured by HPLC-MS/MS. AS IV enhanced CDDP chemosensitivity by increasing tumor cell apoptosis and slowing tumor growth, and decreased kidney injury as evidenced by lower blood creatinine (Cr) and blood urea nitrogen (BUN). Co-administration of AS IV suppressed MRP2 overexpression induced by CDDP in tumor tissues and may be an important mechanism for enhancing CDDP chemosensitivity. Moreover, AS IV reduced CDDP-induced kidney injury in mice along with suppression of OCT2 expression in kidney. The concentration of CDDP was increased in tumor but decreased in kidney. In total, AS IV not only enhanced the antitumor effect of CDDP by suppressing MRP2 expression in tumor cells, but also decreased kidney injury induced by CDDP. The results provide new insight into the combined use of a chemotherapy drug and natural ingredients to treat cancer.

Effect of inter-fractional positional uncertainty on cumulative dose of target volume in intensity-modulated radiotherapy of cervical cancer / 中华放射肿瘤学杂志

Objective:To obtain the inter-fractional set-up errors of intensity-modulated radiotherapy (IMRT) of cervical cancer by cone-beam CT (CBCT), and to analyze the variations of the set-up errors on the cumulative dose deviation of the target volume.Methods:A total of 48 patients with cervical cancer who underwent IMRT were enrolled in this study, and the set-up errors of 696 CBCTs were obtained. The set-up errors were input into the treatment planning system, and the cumulative set-up error dose was obtained by superposing the set-up errors dose. The deviation percentage was calculated by the deviation formula and the standard planning dose.Results:The set-up errors caused the offset of isocenter distance by 0.58(0.36, 0.80) cm. Different statistical differences were noted between the cumulative set-up error dose and the standard planning dose by WilCoxon test. All the dose deviations in the target volume were reduced, and the differential dose volume histogram (DVH) appeared negatively skewed, and the peak value was declined. The DVH diagram shifted to the left with an inverse S-curve and the slope was increased. The HI deviation of the target volume from small to large were: CTV 1, CTV 2, GTV/CTV, CTV 3, CTV n, CTV all, and GTV nd; The HI deviation of the target volume were increased. Conclusions:The effect of set-up errors in IMRT of cervical cancer upon the cumulative doses of the target volume significantly differs. The cumulative dose of the target volume is reduced, and the uniformity of the target volume dose becomes worse. The uncertainty of the inter-fractional position leads to an increase or decrease in the the fractional doses of the target volume. The biological effect on tumor cells and the tumor recurrence remains to be investigated. In IMRT of cervical cancer, the CBCT position calibration is required before each treatment to ensure the dose accuracy of each structure in the target volume.

The DLC-1 tumor suppressor is involved in regulating immunomodulation of human mesenchymal stromal /stem cells through interacting with the Notch1 protein.

BACKGROUND: Immunomodulatory activities of human mesenchymal stromal /stem cells (hMSCs) has been widely recognized as the most critical function of hMSCs for exerting its therapeutic effects. However, the detailed mechanisms responsible for regulating the immunomodulation of hMSCs still remain largely unknown. Previous studies revealed that the Notch1 protein exerted a pro-immunomodulatory function probably through interacting with the protein(s) subjective to proteasome-mediated protein degradation. The DLC-1 protein represents a well characterized tumor suppressor subjective to proteasome-mediated degradation. However, the detailed signaling pathway of Notch1 and the involvement of DLC-1 in regulating the immunomodulation of hMSCs have not been studied before. METHODS: The transfection with cDNA or siRNA into hMSCs assisted by co-culture of hMSCs with peripheral blood mononuclear cells and small molecule inhibitors of signaling proteins, followed by immunoprecipitation, Western blotting, RT-PCR, and flowcytometry, were employed to characterize the Notch1 signaling, to identify DLC-1 as a candidate proteasome-targeted protein, and to characterize DLC-1 signaling pathway and its interaction with the Notch1 signaling, in the regulation of immunomodulation of hMSCs, specifically, the inhibition of pro-inflammatory CD4+-Th1 lymphocytes, and the release of immunomodulatory molecule IDO1. STATISTICAL ANALYSIS: One-way ANOVA was utilized as a statistical tool to analyze the data presented as means ± SEM of at least three separate experiments. RESULTS: The present study revealed that the Notch1-Hey1 axis, but not the Notch1-Hes1 axis, was likely responsible for mediating the pro-immunomodulatory function of the Notch1 signaling. The DLC-1 protein was found subjective to proteasome-mediated protein degradation mediated by the DDB1 and FBXW5 E3 ligases and served as an inhibitor of the immunomodulation of hMSCs through inhibiting Rock1, but not Rock2, downstream the DLC-1 signaling. The Notch1 signaling in the Notch1-Hey1 pathway and the DLC-1 signaling in the DLC-1-Rock1-FBXW5 pathway exhibited a mutual exclusion interaction in the regulation of immunomodulation of hMSCs. CONCLUSIONS: The present study uncovers a novel function of DLC-1 tumor suppressor in regulating the immunomodulation of hMSCs. It also proposes a novel mutual exclusion mechanism between the DLC-1 signaling and the Notch1 signaling that is possibly responsible for fine-tuning the immunomodulation of hMSCs with different clinical implications in hMSCs therapy.

Human lung epithelial BEAS-2B cells exhibit characteristics of mesenchymal stem cells.

BEAS-2B was originally established as an immortalized but non-tumorigenic epithelial cell line from human bronchial epithelium. Because of general recognition for its bronchial epithelial origin, the BEAS-2B cell line has been widely used as an in vitro cell model in a large variety of studies associated with respiratory diseases including lung carcinogenesis. However, very few studies have discussed non-epithelial features of BEAS-2B cells, especially the features associated with mesenchymal stem cells (MSCs), which represent a group of fibroblast-like cells with limited self-renewal and differentiation potential to various cell lineages. In this study, we compared BEAS-2B with a human umbilical cord-derived MSCs (hMSCs) cell line, hMSC1, which served as a representative of hMSCs in terms of expressing common features of hMSCs. It was observed that both BEAS-2B and hMSC1 shared the same expression profile of surface markers of hMSCs and exhibited similar osteogenic and adipogenic differentiation potential. In addition, like hMSC1, the BEAS-2B cell line exhibited suppressive activities on proliferation of mitogen-activated total T lymphocytes as well as Th1 lymphocytes, and IFNγ-induced expression of IDO1, all thus demonstrating that BEAS-2B cells exhibited an almost identical characteristic profile with hMSCs, even though, there was a clear difference between BEAS-2B and hMSCs in the effects on type 2 macrophage polarization. Most importantly, the hMSCs features of BEAS-2B were unlikely a consequence of epithelial-mesenchymal transition. Therefore, this study provided a set of evidence to provoke reconsideration of epithelial origin of BEAS-2B.

DLC-1 tumor suppressor regulates CD105 expression on human non-small cell lung carcinoma cells through inhibiting TGF-ß1 signaling.

Acquisition of features of mesenchymal cells represents a key step of metastatic progression of cancer cells and searching for mechanisms underlying the acquisition will help design novel clinical strategies for suppressing the metastatic progression. The Deleted in Liver Cancer-1 (DLC-1) gene is a p122/RhoGAP tumor/metastatic suppressor gene. However, the mechanism underlying DLC-1's inhibition of metastasis still remains largely unknown. In this study, we revealed that the DLC-1-deficient, but not the DLC-1-competent, human non-small cell lung carcinoma cells (NSCLCs) could acquire the TGF-ß1-induced expression of CD105, a common surface marker of mesenchymal stem cells, with consequent increase in CD105-associated cell motility. Interestingly, the induced CD105 expression and cell motility were subjected to the inhibition by the DLC-1-RhoA-Rock1 signaling through inhibiting the serine phosphorylation at a linker region, but not at the C-terminus, of the Smad3 protein and Smad3 protein nuclear translocation down the canonical TGF-ß1 signaling. In addition, the evidence suggested that DLC-1 very likely exerted its inhibitory effects on the TGF-ß1 signaling and the associated CD105 acquisition in both the cytoplasm and the nucleus. Consistent to the in vitro findings, a reverse correlation between CD105 and DLC-1 in protein expression was identified in primary NSCLC tissues and their surrounding non-tumor tissues. In summary, this study revealed a novel anti-metastasis mechanism governed by the DLC-1 tumor/metastasis suppressor, thus helping design new diagnostic and therapeutic approaches for NSCLCs.

XingNaoJing injections protect against cerebral ischemia/reperfusion injury and alleviate blood-brain barrier disruption in rats, through an underlying mechanism of NLRP3 inflammasomes suppression / 中国天然药物

The aim of this study was to explore the neuroprotective effect and mechanism of XingNaoJing injections (XNJ) on cerebral ischemia injury and blood-brain barrier (BBB) disruption. Middle cerebral artery occlusion (MCAO) method was applicated to establish the model of cerebral ischemia/reperfusion (I/R) injury in rats. BBB permeability after I/R injury was assessed with the leaking amount of Evans Blue and the expression of occludin and ZO-1. The expression of NOD-like receptor family, pyrin domain containing (NLRP3) was checked to explore the inhibition of inflammation by XNJ. The results showed that XNJ could significantly increase the survival percent, decrease the infarct area and ameliorate neurological deficits and brain damage after I/R injury. Leaking amount of Evans Blue was reduced by XNJ, and the expression of tight junction protein, occludin and ZO-1 was also up-regulated by XNJ, which showed a role of protection on BBB disruption. The expression of NLRP3 was inhibited after exposure of XNJ, which was associated with inhibition of the inflammatory response. In summary, XNJ could suppress NLRP3 inflammasomes and improve BBB disruption and brain damage in rats after cerebral I/R injury, which provided a beneficial insight to further explore XNJ.

The hUC-MSCs cell line CCRC-1 represents a novel, safe and high-yielding HDCs for the production of human viral vaccines.

MRC-5 represents the most frequent human diploid cells (HDCs)-type cell substrate in the production of human viral vaccines. However, early-passage MRC-5 is diminishing and, due to both technical and ethical issues, it is extremely difficult to derive novel HDCs from fetal lung tissues, which are the common sources of HDCs. Our previous studies suggested that human umbilical cord may represent an alternative but convenient source of new HDCs. Here, we established a three-tiered cell banking system of a hUC-MSC line, designated previously as Cell Collection and Research Center-1 (CCRC-1). The full characterization indicated that the banked CCRC-1 cells were free from adventitious agents and remained non-tumorigenic. The CCRC-1 cells sustained its rapid proliferation even at passage 30 and were susceptible to the infection of a wide spectrum of viruses. Interestingly, the CCRC-1 cells showed much higher production of EV71 or Rubella viruses than MRC-5 and Vero cells when growing in serum-free medium. More importantly, the EV71 vaccine produced from CCRC-1 cells induced immunogenicity while eliciting no detectable toxicities in the tested mice. Collectively, these studies further supported that CCRC-1, and likely other hUC-MSCs as well, may serve as novel, safe and high-yielding HDCs for the production of human viral vaccines.

RIG-I and IL-6 are negative-feedback regulators of STING induced by double-stranded DNA.

The stimulator of interferon genes (STING) protein has emerged as a critical signal transduction molecule in the innate immune response. Sustained activation of the STING signaling induced by cytosolic DNA has been considered to be the cause of a variety of autoimmune diseases characterized by uncontrolled inflammation. Therefore, it is important to understand the molecular basis of the regulation of STING signaling pathway. Here we demonstrate that the STING protein undergoes a proteasome-mediated degradation in human diploid cell (HDC) lines including MRC-5 following the transfection of double-stranded DNA (dsDNA). The degradation of STING is accompanied by the increased expression of both RIG-I and IL-6. Employing the RIG-I siRNA knockdown and an IL-6 neutralizing antibody greatly inhibits the degradation of STING induced by dsDNA. We further demonstrate that both IL-6 and RIG-I are downstream molecules of STING along the DNA sensor pathway. Therefore, STING degradation mediated by RIG-I and IL-6 may serve as a negative feedback mechanism to limit the uncontrolled innate immune response induced by dsDNA. We have further shown that RIG-I and IL-6 promote STING degradation by activating/dephosphorylating UNC-51-like kinase (ULK1). Interestingly, the STING protein is not significantly affected by dsDNA in non-HDC HEK293 cells. Our study thus has identified a novel signaling pathway for regulating STING in HDCs.

An investigation of ketoacidosis in children with newly diagnosed type 1 diabetes / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To investigate the incidence of diabetic ketoacidosis (DKA) in children with newly diagnosed type 1 diabetes.</p><p><b>METHODS</b>A retrospective analysis was performed for the clinical data of 224 children with newly diagnosed type 1 diabetes, and according to the presence or absence of DKA, these children were divided into DKA group and non-DKA group, with 112 children in each group. The DKA group was further divided into ≥5-year group (65 children) and <5-year group (47 children), and according to the blood gas parameters, this group was divided into mild group (26 children), moderate group (29 children), and severe group (57 children). The factors influencing the development of DKA were analyzed, as well as the clinical and laboratory features of DKA children with different ages.</p><p><b>RESULTS</b>The most common symptoms in these 224 children with type 1 diabetes were polydipsia (86.2%), polyuria (78.6%), and weight loss (57.1%). Compared with the non-DKA group, the DKA group had a significantly higher percentage of children who were aged <5 years, who had low family income, or whose parents had an educational level of senior high school or below. The DKA group had significantly higher levels of random blood glucose and HbA1C and significantly lower levels of pH, HCO3, and C-peptide than the non-DKA group (P<0.05). There was no significant difference in the percentage of children with severe DKA between the ≥5-year group and the <5-year group (P>0.05). Compared with the <5-year group, the ≥5-year group sufferred from symptoms for a significantly prolonged period, and had a significantly lower level of random blood glucose and significantly higher levels of HbA1C and C-peptide (P<0.05).</p><p><b>CONCLUSIONS</b>DKA has a high incidence rate in children with type 1 diabetes, and the development of DKA is associated with age, parents' educational level, and family income.</p>

The application of flipped classroom based on WeChat and TBL in the teaching of nutrition and food hygiene / 中华医学教育探索杂志

There were some shortcomings for traditional teaching mode of nutrition and food hygiene course, such as many teaching contents and little teaching time, students much passively learning and little active learning. We explored the combination of the WeChat and the TBL teaching to conduct the flipped classroom to solve the deficiency. The teaching pattern was conducted in 60 students majoring in preventive medicine from Grade 2012. The learning task of nutrition and food hygiene was released on the WeChat before the class. Students learned knowledge in the form of discussion based on case in the class. After the class, the discussion, answer the question and test were conducted on the WeChat. The survey showed that 85% of the students were satisfied with teaching pattern,especially satisfied with its role of broadening students' knowledge and vision, improving their autonomous learning ability, teamwork ability, and their ability to analyze and solve problems.

Therapeutic Effect of Entecavir Combined with Vitamin E in the Treatment of Chronic Hepatitis B Complicated with Non-alcoholic Fatty Liver / 现代医院

Objective To explore the clinical efficacy of entecavir combined with Vitamin E in treating patients with Chronic hepatitis B complicated with non-alcoholic fatty liver.Methods Retrospective analysis was done by reviewing the clinical data of 103 patients, who suffered with chronic hepatitis B complicated with non-alcoholic fatty liver and treated in our hospital from 2015 to 2016.The patients were divided into the control group with 61 cases and the observation group with 42 cases based on different therapies.The control group was treated with only entecavir while the observation group was treated with entecavir and Vitamin E, and both the courses of treatment lasted for 6 months.The negative conversion ratio of HBV-DNA, levels of ALT, TBIL, ALP, the disease state and the adverse reactions of the two groups were compared before and after treatment.Results The negative conversion ratio of HBV-DNA of the observation group was obviously higher than that of the control group, and the patients of the observation group showed significant improvement.Meanwhile, the levels of ALT, TBIL and ALP in the two groups were both lower than before treatment.Compared with the control group, those indexes in the observation group were significantly lower (P<0.05).Conclusion Entecavir combined with Vitamin E for the treatment of chronic hepatitis B complicated with non-alcoholic fatty liver could significantly decrease the viral infections so that the state of patients can be improved.

The notch signaling regulates CD105 expression, osteogenic differentiation and immunomodulation of human umbilical cord mesenchymal stem cells.

Mesenchymal stem cells (MSCs) are a group of multipotent cells with key properties of multi-lineage differentiation, expressing a set of relatively specific surface markers and unique immunomodulatory functions. IDO1, a catabolic enzyme of tryptophan, represents a critical molecule mediating immunomodulatory functions of MSCs. However, the signaling pathways involved in regulating these key properties still remain elusive. To investigate the involvement of Notch signaling as well as other potential signaling pathway(s) in regulating these critical properties of MSCs, we treated human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) with γ-secreatase inhibitor I (GSI-I), which inhibits both Notch signaling and ubiquitin-proteasome activities. It was shown that the GSI-I treatment resulted in apoptosis, reduced expression of surface markers CD73, CD90 and CD105, reduced osteogenic differentiation, and reduction of the hUC-MSCs-mediated suppression of Th1 lymphocyte proliferation and the IFN-γ-induced IDO1 expression. Through distinguishing the effects of GSI-I between Notch inhibition and proteasome inhibition, it was further observed that, whereas both Notch inhibition and proteasome inhibition were attributable to the reduced CD105 expression and osteogenic differentiation, but not to the induced apoptosis. However, Notch inhibition, but not proteasome inhibition, only contributed to the significant effect of GSI-I on Th1 proliferation probably through reducing IDO1 promoter activity. In conclusion, the Notch signaling may represent a very important cell signaling capable of regulating multiple critical properties, especially the immunomodulatory functions of MSCs.

Human diploid MRC-5 cells exhibit several critical properties of human umbilical cord-derived mesenchymal stem cells.

MRC-5 is the most common human diploid cell line used in production of viral vaccines; mesenchymal stem cells (MSCs) is a type of adult multipotent stem cells. Both cell types share the same fibroblast-like morphology and maintain a normal diploid karyotype over long in vitro expansion. However, other than these similarities, very little is known about MRC-5 in terms of biological properties possessed by MSCs. In this study, we compared MRC-5 with human umbilical cord-derived MSCs (hUC-MSCs), which serves as a representative of human MSCs, in expression of cell surface markers, abilities to differentiate into multiple cell lineages, inhibition of lymphocyte proliferation and promotion of Regulatory T lymphocytes (Treg), and IDO1 expression in response to inflammatory cytokines, all of which are critical properties of MSCs. It was revealed that MRC-5 was almost identical to hUC-MSCs in expression of both positive and negative surface markers of MSCs. Similar to hUC-MSCs, MRC-5 was also able to differentiate into osteocytes and chondrocytes, effectively inhibit mitogen-activated lymphocyte proliferation and promote Tregs, and express IDO1 in response to inflammatory cytokines IFN-γ and TNF-α. In addition, both MRC-5 and hUC-MSCs were non-tumorigenic with an extremely low telomerase activity. Moreover, both cells demonstrated a similar sensitivity to infection by EV71 and rubella viruses, which served as model viruses, in a virus infectivity assay. Therefore, this study suggests that MRC-5 is very likely a previously undefined MSC cell line, thus suggesting the feasibility of developing MSCs of at least umbilical cord origin as new cell substrates to be used in production of viral vaccines.

TRPV5: a Ca(2+) channel for the fine-tuning of Ca(2+) reabsorption.

TRPV5 is one of the two channels in the TRPV family that exhibit high selectivity to Ca(2+) ions. TRPV5 mediates Ca(2+) influx into cells as the first step to transport Ca(2+) across epithelia. The specialized distribution in the distal tubule of the kidney positions TRPV5 as a key player in Ca(2+) reabsorption. The responsiveness in expression and/or activity of TRPV5 to hormones such as 1,25-dihydroxyvitamin D3, parathyroid hormone, estrogen, and testosterone makes TRPV5 suitable for its role in the fine-tuning of Ca(2+) reabsorption. This role is further optimized by the modulation of TRPV5 trafficking and activity via its binding partners; co-expressed proteins; tubular factors such as calbindin-D28k, calmodulin, klotho, uromodulin, and plasmin; extracellular and intracellular factors such as proton, Mg(2+), Ca(2+), and phosphatidylinositol-4,5-bisphosphate; and fluid flow. These regulations allow TRPV5 to adjust its overall activity in response to the body's demand for Ca(2+) and to prevent kidney stone formation. A point mutation in mouse Trpv5 gene leads to hypercalciuria similar to Trpv5 knockout mice, suggesting a possible role of TRPV5 in hypercalciuric disorders in humans. In addition, the single nucleotide polymorphisms in Trpv5 gene prevalently present in African descents may contribute to the efficient renal Ca(2+) reabsorption among African descendants. TRPV5 represents a potential therapeutic target for disorders with altered Ca(2+) homeostasis.

Disease-causing R1185C mutation of WNK4 disrupts a regulatory mechanism involving calmodulin binding and SGK1 phosphorylation sites.

The R1185C mutation in WNK4 is associated with pseudohypoaldosteronism type II (PHAII). Unlike other PHAII-causing mutations in the acidic motif, the R1185C mutation is located in the COOH-terminal region of WNK4. The goal of the study is to determine what properties of WNK4 are disrupted by the R1185C mutation. We found that the R1185C mutation is situated in the middle of a calmodulin (CaM) binding site and the mutation reduces the binding of WNK4 to Ca(2+)/CaM. The R1185C mutation is also close to serum- and glucocorticoid-induced protein kinase (SGK1) phosphorylation sites S1190 and S1217. In addition, we identified a novel SGK1 phosphorylation site (S1201) in WNK4, and phosphorylation at this site is reduced by Ca(2+)/CaM. In the wild-type WNK4, the level of phosphorylation at S1190 is the lowest and that at S1217 is the highest. In the R1185C mutant, phosphorylation at S1190 is eliminated and that at S1201 becomes the strongest. The R1185C mutation enhances the positive effect of WNK4 on the Na(+)-K(+)-2Cl(-) cotransporter 2 (NKCC2) as tested in Xenopus laevis oocytes. Deletion of the CaM binding site or phospho-mimicking at two or three of the SGK1 sites enhances the WNK4 effects on NKCC2. These results indicate that the R1185C mutation disrupts an inhibitory domain as part of the suppression mechanism of WNK4, leading to an elevated WNK4 activity at baseline. The presence of CaM binding and SGK1 phosphorylation sites in or close to the inhibitory domain suggests that WNK4 activity is subject to the regulation by intracellular Ca(2+) and phosphorylation.