Activated mesenchymal stem/stromal cells promote myeloid cell differentiation via CCL2/CCR2 signaling.

Myeloid cells, which originate from hematopoietic stem/progenitor cells (HSPCs), play a crucial role in mitigating infections. This study aimed to explore the impact of mesenchymal stem/stromal cells (MSCs) on the differentiation of HSPCs and progenitors through the C-C motif chemokine CCL2/CCR2 signaling pathway. Murine MSCs, identified as PDGFRα+Sca-1+ cells (PαS cells), were found to secrete CCL2, particularly in response to lipopolysaccharide stimulation. MSC-secreted CCL2 promoted the differentiation of granulocyte/macrophage progenitors into the myeloid lineage. MSC-derived CCL2 plays an important role in the early phase of myeloid cell differentiation in vivo. Single-cell RNA sequencing analysis confirmed that CCL2-mediated cell fate determination was also observed in human bone marrow cells. These findings provide valuable insights for investigating the in vivo effects of MSC transplantation.

Quality Control of Stem Cell-Based Cultured Meat According to Specific Differentiation Abilities.

The demand for stem cell-based cultured meat as an alternative protein source is increasing in response to global food scarcity. However, the definition of quality controls, including appropriate growth factors and cell characteristics, remains incomplete. Cluster of differentiation (CD) 29 is ubiquitously expressed in bovine muscle tissue and is a marker of progenitor cells in cultured meat. However, CD29+ cells are naturally heterogeneous, and this quality control issue must be resolved. In this study, the aim was to identify the subpopulation of the CD29+ cell population with potential utility in cultured meat production. The CD29+ cell population exhibited heterogeneity, discernible through the CD44 and CD344 markers. CD29+CD44-CD344- cells displayed the ability for long-term culture, demonstrating high adipogenic potential and substantial lipid droplet accumulation, even within 3D cultures. Conversely, CD29+CD44+ cells exhibited rapid proliferation but were not viable for prolonged culture. Using cells suitable for adipocyte and muscle differentiation, we successfully designed meat buds, especially those rich in fat. Collectively, the identification and comprehension of distinct cell populations within bovine tissues contribute to quality control predictions in meat production. They also aid in establishing a stable and reliable cultured meat production technique.

A novel mouse model of intestinal neuronal dysplasia: visualization of the enteric nervous system.

PURPOSE: Intestinal neuronal dysplasia (IND) is a congenital anomaly affecting gastrointestinal neural innervation, but the pathogenesis remains unclear. The homozygous Ncx/Hox11L.1 knockout (Ncx-/-) mice exhibit megacolon and enteric ganglia anomalies, resembling IND phenotypes. Sox10-Venus transgenic mouse were used to visualize enteric neural crest cells in real time. This study aims to establish a novel mouse model of Sox10-Venus+/Ncx-/- mouse to study the pathogenesis of IND. METHODS: Sox10-Venus+/Ncx-/- (Ncx-/-) (n = 8) mice and Sox10-Venus+/Ncx+/+ controls (control) (n = 8) were euthanized at 4-5 weeks old, and excised intestines were examined with fluorescence microscopy. Immunohistochemistry was performed on tissue sections with neural marker Tuj1. RESULTS: Ncx-/- mice exhibited dilated cecum and small intestine. Body weight of Ncx-/- mice was lower with higher ratio of small intestine length relative to body weight. The neural network (Sox10-Venus) was observed along the intestine wall in Ncx-/- and control mice without staining. Ectopic and increased expression of Tuj1 was observed in both small intestine and proximal colon of Ncx-/- mice. CONCLUSION: This study has established a reliable animal model that exhibits characteristics similar to patients with IND. This novel mouse model can allow the easy visualization of ENS in a time- and cost-effective way to study the pathogenesis of IND.

The impact of the recipient intestinal site on the differentiation of transplanted enteric neural crest cells.

PURPOSE: It has long been established that the failure of enteric neural crest cells (ENCCs) to colonize the entire gut results in aganglionosis at the distal colon in Hirschsprung disease (HD). However, it is still unclear how the intestinal microenvironment of the distal aganglionic gut differs from that of the proximal ganglionic gut in HD versus normal gut. We have recently succeeded in transplanting ENCC into aganglionic gut in endothelin receptor B (Ednrb) knockout (KO) mice. to advance the development of cell therapy for HD, it is essential to determine if the transplanted ENCCs differentiate normally in aganglionic gut. Therefore, we designed this study to investigate the impact of the environment of the recipient intestinal tract, at various sites of aganglionic gut, on the differentiation of transplanted ENCCs. METHODS: ENCCs were isolated from Sox10 Venus transgenic (Tg) mouse gut on embryonic day 18.5 (E18.5) and neurospheres (NS) were generated. Then, NS were transplanted into aganglionic KO and wildtype (WT) gut that had been transected just distal to the ENCC wavefront (KO-wf: n = 6, WT: n = 7), and into distal KO gut transected at a site equivalent to that of the WT (KO-d: n = 6) on E12.5. ENCC differentiation was evaluated using whole-mount immunohistochemistry with Tuj-1 (neuronal marker) and GFAP (glial marker) antibodies. RESULTS: The transplanted ENCCs migrated to form the myenteric and submucosal plexus in all groups. The ratio of the area of Tuj-1-positive cells/GFAP-positive cells in migrated cells in the recipient gut was found to be significantly lower in KO-d compared to KO-wf and WT, while there was no significant difference between KO-wf and WT groups. This suggests that neuronal/glial differentiation was decreased in KO-d compared to that in KO-wf and WT groups. CONCLUSION: Our study highlights the differences in ENCC differentiation depending on the site of transplantation. To further develop cell therapy for HD, it is important to consider the impact of the recipient intestinal environment on transplanted ENCCs.

Conservation of Markers and Stemness in Adipose Stem and Progenitor Cells between Cattle and Other Species.

Adipose stem and progenitor cells (ASPCs) have been isolated from humans and animals for use in regenerative medicine and therapy. However, knowledge of ASPCs in other species is limited. Particularly, ASPCs in livestock are expected to enhance the fat content and meat composition. In this study, we isolated bovine ASPCs using cell surface markers. Specifically, we focused on ASPC markers in humans and experimental animals, namely CD26, CD146, and CD54. Stromal vascular fraction cells from bovine fat were separated using flow cytometry before primary culture. We evaluated the self-renewal and adipogenic potential of each fraction. We identified four cell populations: CD26-CD146+CD54+, CD26-CD146+CD54-, CD26-CD146-, and CD26+CD146-. Among them, the CD26-CD146+ fraction, particularly CD54+, demonstrated the properties of preadipocytes (PreAs), characterized by slow proliferation and a high adipogenic capacity. In conclusion, we could collect and characterize possible PreAs as CD26-CD146+CD54+ or CD26-CD146+CD54-, which are expected for in vitro bovine adipogenic assays in the future.

CD73-Positive Cell Spheroid Transplantation Attenuates Colonic Atrophy.

The incidence of inflammatory bowel diseases (IBD) is increasing worldwide. Mesenchymal stem/stromal cells (MSCs) have immunomodulatory functions and are a promising source for cell transplantation therapy for IBD. However, owing to their heterogeneous nature, their therapeutic efficacy in colitis is controversial and depends on the delivery route and form of transplanted cells. Cluster of differentiation (CD) 73 is widely expressed in MSCs and used to obtain a homogeneous MSC population. Herein, we determined the optimal method for MSC transplantation using CD73+ cells in a colitis model. mRNA sequencing analysis showed that CD73+ cells exhibited a downregulation of inflammatory gene expression and an upregulation of extracellular matrix-related gene expression. Furthermore, three-dimensional CD73+ cell spheroids showed enhanced engraftment at the injured site through the enteral route, facilitated extracellular matrix remodeling, and downregulated inflammatory gene expression in fibroblasts, leading to the attenuation of colonic atrophy. Therefore, the interaction between intestinal fibroblasts and exogenous MSCs via tissue remodeling is one mechanism that can be exploited for colitis prevention. Our results highlight that the transplantation of homogeneous cell populations with well-characterized properties is beneficial for IBD treatment.

Three-dimensional visualization of neural networks inside bone by Osteo-DISCO protocol and alteration of bone remodeling by surgical nerve ablation.

Bone is one of the largest organ systems in humans and is considered to regulate whole-body homeostasis in cooperation with other organs. We have previously reported that a sympathetic or sensory nervous system inside bone regulates bone homeostasis. However, the detailed regulatory mechanism, including the distribution of nerves inside bone, remains unknown. Although a two-dimensional histological analysis has been widely used to evaluate the structure of nerves or blood vessels, the actual structure is more complex, suggesting that it should be evaluated three-dimensionally. Here, we established a novel bone tissue clearing technique (Osteo-DISCO) for murine bones which enabled us to visualize the detailed distribution of nerves or blood vessels inside bone. Interestingly, we found that there is a specific nerve entry site in each long bone and that surgical ablation of the specific nerve fibers entering bone tissue led to decreased bone formation and impaired bone regeneration. Furthermore, we revealed that the administration of calcitonin gene-related peptide (CGRP), which is primarily released from sensory nerves, suppressed the bone loss caused by surgical nerve ablation. An in vitro study also indicated that CGRP directly promotes osteoblast activity, suggesting that sensory nerves inside bone can regulate osteogenesis via the secretion of CGRP.

Evaluation of Human-Induced Pluripotent Stem Cells Derived from a Patient with Schwartz-Jampel Syndrome Revealed Distinct Hyperexcitability in the Skeletal Muscles.

Schwartz-Jampel syndrome (SJS) is an autosomal recessive disorder caused by loss-of-function mutations in heparan sulfate proteoglycan 2 (HSPG2), which encodes the core basement membrane protein perlecan. Myotonia is a major criterion for the diagnosis of SJS; however, its evaluation is based solely on physical examination and can be challenging in neonates and young children. Furthermore, the pathomechanism underlying SJS-related myotonia is not fully understood, and effective treatments for SJS are limited. Here, we established a cellular model of SJS using patient-derived human-induced pluripotent stem cells. This model exhibited hyper-responsiveness to acetylcholine as a result of abnormalities in the perlecan molecule, which were confirmed via comparison of their calcium imaging with calcium imaging of satellite cells derived from Hspg2-/--Tg mice, which exhibit myotonic symptoms similar to SJS symptoms. Therefore, our results confirm the utility of creating cellular models for investigating SJS and their application in evaluating myotonia in clinical cases, while also providing a useful tool for the future screening of SJS therapies.

Increased enteric neural crest cell differentiation after transplantation into aganglionic mouse gut.

PURPOSE: In recent years, many studies have made considerable progress in the development of stem cell-based therapies for Hirschsprung's disease (HD). However, the question of whether enteric neural crest-derived cells (ENCCs) that are transplanted into the aganglionic gut can migrate, proliferate, and differentiate in a normal manner remains unanswered. Thus, we designed this study to compare the behavior of ENCCs transplanted into the aganglionic gut of endothelin receptor B knockout (Ednrb-KO) mice versus wild-type (WT) mice. METHODS: ENCCs were isolated from the fetal guts of Sox10 transgenic mice, in which ENCCs were labeled with an enhanced green fluorescent protein, Venus, on an embryonic day 18.5 (E18.5). Neurospheres were generated and transplanted into the aganglionic region of either Ednrb-KO mice gut, or WT mice gut that had not yet been colonized, on E12.5. Time-lapse imaging of the transplanted ENCCs was performed after 24, 48, and 72 h of culture. Neuronal differentiation was evaluated using whole-mount immunohistochemistry. RESULTS: Sox10-positive ENCCs were seen to successfully migrate into the myenteric region of the aganglionic gut following transplantation in both the Ednrb-KO and WT mice. The ratio of Tuj1-positive/Sox10-positive cells was significantly increased after 72 h of culture compared to 24 h in the Ednrb-KO mice, which suggests that the transplanted ENCCs differentiated over time. In addition, at the 72 h timepoint, neuronal differentiation of transplanted ENCC in the aganglionic gut of Ednrb-KO mice was significantly increased compared to that of WT mice. CONCLUSIONS: The results of our study demonstrated that transplanted ENCCs migrated into the myenteric region of the aganglionic recipient gut in mice. The increased neuronal differentiation of transplanted ENCC in Endrb-KO mice gut suggests that the microenvironment of this region affects ENCC behavior following transplantation. Further research to explore the characteristics of this microenvironment will improve the potential of developing cell therapy to treat HD patients.

Differentiation of enteric neural crest cells transplanted from SOX10-Venus mouse embryonic stem cells into the gut of the endothelin receptor B null mouse model.

PURPOSE: Failure of enteric neural crest-derived cells (ENCCs) to correctly colonize the embryonic gut results in Hirschsprung's disease (HD). Embryonic stem cells (ESCs) have the potential to differentiate into all tissue-specific cells and lineages, including ENCCs. We investigated the cellular differentiation of ESCs from Sox10-Venus + mice into both control and endothelin receptor-B knockout (Ednrb KO) mouse gut to assess each region. METHODS: We established ESCs from Sox10-Venus + mice. These cells were cultured for 2 days, then selected and co-cultured with either a dissociated control or Sox10-Venus - Ednrb KO mouse gut (both small intestine and colon) on embryonic day (E) 13.5. Four days later, cells were immunolabeled for Tuj1 and visualized using confocal microscopy. RESULTS: Confocal microscopy revealed that transplanted Sox10-Venu + cells from ESCs migrated extensively within the host gut. Moreover, Tuj1-positive neurites were detected in the transplanted ESCs. Tuj1 expression was significantly decreased in aganglionic HD colon compared to controls (p < 0.05) and the HD small intestine (p < 0.05). CONCLUSIONS: This study demonstrated that an appropriate host environment is crucial for normal and complete colonization of the gut. Further investigations are required to confirm whether modifying this environment can improve the results of this model.

Longitudinal Analyses after COVID-19 Recovery or Prolonged Infection Reveal Unique Immunological Signatures after Repeated Vaccinations.

To develop preventive and therapeutic measures against coronavirus disease 2019, the complete characterization of immune response and sustained immune activation following viral infection and vaccination are critical. However, the mechanisms controlling intrapersonal variation in antibody titers against SARS-CoV-2 antigens remain unclear. To gain further insights, we performed a robust molecular and cellular investigation of immune responses in infected, recovered, and vaccinated individuals. We evaluated the serum levels of 29 cytokines and their correlation with neutralizing antibody titer. We investigated memory B-cell response in patients infected with the original SARS-CoV-2 strain or other variants, and in vaccinated individuals. Longitudinal correlation analyses revealed that post-vaccination neutralizing potential was more strongly associated with various serum cytokine levels in recovered patients than in naïve individuals. We found that IL-10, CCL2, CXCL10, and IL-12p40 are candidate biomarkers of serum-neutralizing antibody titer after the vaccination of recovered individuals. We found a similar distribution of virus-specific antibody gene families in triple-vaccinated individuals and a patient with COVID-19 pneumonia for 1 year. Thus, distinct immune responses occur depending on the viral strain and clinical history, suggesting that therapeutic options should be selected on a case-by-case basis. Candidate biomarkers that correlate with repeated vaccination may support the efficacy and safety evaluation systems of mRNA vaccines and lead to the development of novel vaccine strategies.

Hematopoietic-Mesenchymal Signals Regulate the Properties of Mesenchymal Stem Cells.

It is well known that the properties of hematopoietic stem/progenitor cells (HSCs), such as their self-renewal ability and multipotency, are maintained through interactions with mesenchymal stem/stromal cells (MSCs). MSCs are rare cells that are present in the bone marrow and are useful for clinical applications due to their functional ability. To obtain the necessary number of cells, MSCs must be cultured to expand, but this causes a remarkable decrease in stem cell properties, such as multipotency and proliferation ability. In this study, we show that the c-Mpl signal, which is related to the maintenance of hematopoietic stem cells, has an important effect on the proliferation and differentiation ability of MSCs. Utilizing a co-culture system comprising MSCs and HSCs, it is suggested that signaling from hematopoietic cells to MSCs supports cell proliferation. Interestingly, the enhanced proliferation ability of the HSCs was decreased in c-Mpl knock-out HSCs (c-Mpl-KO). In addition, the MSCs co-cultured with c-Mpl-KO HSCs had reduced MSC marker expression (PDGFRa and Sca-1) compared to the MSCs co-cultured with c-Mpl-wild-type HSCs. These results suggest that a hematopoietic-mesenchymal signal exists, and that the state of the HSCs is important for the stability of MSC properties.

In vitro investigation of the differentiation of enteric neural crest-derived cells following transplantation of aganglionic gut in a mouse model.

PURPOSE: Cell therapy is a promising approach to treat enteric neuropathies such as Hirschsprung disease (HD). Recent studies have reported that enteric neurons derived from stem cells (ENCCs) can be grafted into the HD colon. Thus, we investigated the migration and generation of enteric neurospheres from SOX10-VENUS+ mice after transplantation into control or Ednrb KO mice, which are a model of HD. METHODS: Single-cell suspensions were isolated from the fetal guts of SOX10-VENUS+ mice E13.5 and dissociated. These cells were cultured for 7 days under non-adherent conditions to generate neurospheres, which were co-cultured with dissociated control or SOX10-VENUS- Ednrb KO mouse gut on E13.5. 4 days later, these cells were fixed and the expression of the neuronal marker, Tuj1, was evaluated. RESULTS: Transplanted neurospheres had undergone abundant neuronal migration and differentiation of ENCCs in the control gut compared with the HD gut. The average length and intersections were significantly decreased in HD colon compared with controls (p < 0.05), and a similar pattern was observed in the HD small intestine (p < 0.05). CONCLUSIONS: We demonstrated that transplanted ENCCs did not differentiate properly in HD gut. These results highlight the importance of the neuronal environment in the recipient gut for enteric nervous system development.

DNA/RNA heteroduplex oligonucleotide technology for regulating lymphocytes in vivo.

Manipulating lymphocyte functions with gene silencing approaches is promising for treating autoimmunity, inflammation, and cancer. Although oligonucleotide therapy has been proven to be successful in treating several conditions, efficient in vivo delivery of oligonucleotide to lymphocyte populations remains a challenge. Here, we demonstrate that intravenous injection of a heteroduplex oligonucleotide (HDO), comprised of an antisense oligonucleotide (ASO) and its complementary RNA conjugated to α-tocopherol, silences lymphocyte endogenous gene expression with higher potency, efficacy, and longer retention time than ASOs. Importantly, reduction of Itga4 by HDO ameliorates symptoms in both adoptive transfer and active experimental autoimmune encephalomyelitis models. Our findings reveal the advantages of HDO with enhanced gene knockdown effect and different delivery mechanisms compared with ASO. Thus, regulation of lymphocyte functions by HDO is a potential therapeutic option for immune-mediated diseases.

Patients with mild cognitive impairment diagnosed at dementia clinic display decreased maximum occlusal force: a cross-sectional study.

BACKGROUND: Previous research indicates that patients with mild cognitive impairment (MCI) are more likely to have poor oral health and impairments in oral functions, which may be due to few remaining teeth and impaired tongue and lip motor function. However, the oral health of those patients following comprehensive cognitive assessment by a dementia specialist has not been sufficiently investigated. Therefore, this study aimed to clarify the oral function of patients with MCI and the association between oral health and lower cognitive function. METHODS: This cross-sectional study included 96 participants (men: 35; women: 61; mean age: 73.3 ± 8.5 years) who visited a dementia clinic between December 2017 and January 2020. Participants' cognitive function was assessed by a dementia specialist using neuropsychological and hematological tests and neuroimaging immediately after enrollment. The participants were divided into the healthy and MCI groups according to comprehensive cognitive assessment. Participants' age, sex, body mass index, primary disease, education level, drinking habits, smoking habits, living environment, employment status, and exercise habits were evaluated. Moreover, oral outcomes, including the number of existing teeth, number of functional teeth (natural and prosthetic teeth which were occluded with antagonists), denture use, oral dryness, tongue and lip motor function, tongue pressure, occlusal force, masticatory ability, and swallowing ability were recorded. The Mann-Whitney U test, χ2, and Fisher's exact tests were used for between-group comparisons. Furthermore, logistic regression analysis using MCI diagnosis as the target variable was performed. RESULTS: A comprehensive evaluation of the cognitive function of the study participants by the dementia specialist revealed that 48 participants (mean age: 69.8 ± 8.8 years) were healthy and 48 (mean age: 76.9 ± 6.7 years) had MCI. MCI participants were significantly older (p < 0.001) and had significantly fewer existing teeth (p = 0.031) and lower maximum occlusal force (p = 0.019) than healthy participants. Age (odds ratio: 1.126, p = 0.002) and maximum occlusal force (odds ratio: 0.978, p = 0.048) were significantly associated with lower cognitive function. CONCLUSIONS: Patients with MCI had poorer oral health than healthy individuals. Decreased maximum occlusal force was independently associated with lower cognitive function, even when adjusted for age and sex.

Isolation and Characterization of Tissue Resident CD29-Positive Progenitor Cells in Livestock to Generate a Three-Dimensional Meat Bud.

The current process of meat production using livestock has significant effects on the global environment, including high emissions of greenhouse gases. In recent years, cultured meat has attracted attention as a way to acquire animal proteins. However, the lack of markers that isolate proliferating cells from bovine tissues and the complex structure of the meat make it difficult to culture meat in a dish. In this study, we screened 246 cell-surface antibodies by fluorescence-activated cell sorting for their capacity to form colonies and their suitability to construct spheroid "meat buds". CD29+ cells (Ha2/5 clone) have a high potency to form colonies and efficiently proliferate on fibronectin-coated dishes. Furthermore, the meat buds created from CD29+ cells could differentiate into muscle and adipose cells in a three-dimensional structure. The meat buds embedded in the collagen gel proliferated in the matrix and formed large aggregates. Approximately 10 trillion cells can theoretically be obtained from 100 g of bovine tissue by culturing and amplifying them using these methods. The CD29+ cell characteristics of bovine tissue provide insights into the production of meat alternatives in vitro.

Cellular Heterogeneity of Mesenchymal Stem/Stromal Cells in the Bone Marrow.

Mesenchymal stem/stromal cells (MSCs) are present in various body tissues and help in maintaining homeostasis. The stemness of MSCs has been evaluated in vitro. In addition, analyses of cell surface antigens and gene expression patterns have shown that MSCs comprise a heterogeneous population, and the diverse and complex nature of MSCs makes it difficult to identify the specific roles in diseases. There is a lack of understanding regarding the classification of MSC properties. In this review, we explore the characteristics of heterogeneous MSC populations based on their markers and gene expression profiles. We integrated the contents of previously reported single-cell analysis data to better understand the properties of mesenchymal cell populations. In addition, the cell populations involved in the development of myeloproliferative neoplasms (MPNs) are outlined. Owing to the diversity of terms used to describe MSCs, we used the text mining technology to extract topics from MSC research articles. Recent advances in technology could improve our understanding of the diversity of MSCs and help us evaluate cell populations.

Soluble JAM-C Ectodomain Serves as the Niche for Adipose-Derived Stromal/Stem Cells.

Junctional adhesion molecules (JAMs) are expressed in diverse types of stem and progenitor cells, but their physiological significance has yet to be established. Here, we report that JAMs exhibit a novel mode of interaction and biological activity in adipose-derived stromal/stem cells (ADSCs). Among the JAM family members, JAM-B and JAM-C were concentrated along the cell membranes of mouse ADSCs. JAM-C but not JAM-B was broadly distributed in the interstitial spaces of mouse adipose tissue. Interestingly, the JAM-C ectodomain was cleaved and secreted as a soluble form (sJAM-C) in vitro and in vivo, leading to deposition in the fat interstitial tissue. When ADSCs were grown in culture plates coated with sJAM-C, cell adhesion, cell proliferation and the expression of five mesenchymal stem cell markers, Cd44, Cd105, Cd140a, Cd166 and Sca-1, were significantly elevated. Moreover, immunoprecipitation assay showed that sJAM-C formed a complex with JAM-B. Using CRISPR/Cas9-based genome editing, we also demonstrated that sJAM-C was coupled with JAM-B to stimulate ADSC adhesion and maintenance. Together, these findings provide insight into the unique function of sJAM-C in ADSCs. We propose that JAMs contribute not only to cell-cell adhesion, but also to cell-matrix adhesion, by excising their ectodomain and functioning as a niche-like microenvironment for stem and progenitor cells.

Comparison of the clinical performance and usefulness of five SARS-CoV-2 antibody tests.

We examined the usefulness of five COVID-19 antibody detection tests using 114 serum samples at various time points from 34 Japanese COVID-19 patients. We examined Elecsys Anti-SARS-CoV-2 from Roche, and four immunochromatography tests from Hangzhou Laihe Biotech, Artron Laboratories, Chil, and Nadal. In the first week after onset, Elecsys had 40% positivity in Group S (severe cases) but was negative in Group M (mild-moderate cases). The immunochromatography kits showed 40-60% and 0-8% positivity in Groups S and M, respectively. In the second week, Elecsys showed 75% and 50% positivity, and the immunochromatography tests showed 5-80% and 50-75% positivity in Groups S and M, respectively. After the third week, Elecsys showed 100% positivity in both groups. The immunochromatography kits showed 100% positivity in Group S. In Group M, positivity decreased to 50% for Chil and 75-89% for Artron and Lyher. Elecsys and immunochromatography kits had 91-100% specificity. Elecsys had comparable chronological change of cut-off index values in the two groups from the second week to the sixth week. The current SARS-CoV-2 antibody detection tests do not provide meaningful interpretation of severity and infection status. Its use might be limited to short-term epidemiological studies.

FZD5 regulates cellular senescence in human mesenchymal stem/stromal cells.

Human mesenchymal stem/stromal cells (hMSCs) have garnered enormous interest as a potential resource for cell-based therapies. However, the molecular mechanisms regulating senescence in hMSCs remain unclear. To elucidate these mechanisms, we performed gene expression profiling to compare clonal immature MSCs exhibiting multipotency with less potent MSCs. We found that the transcription factor Frizzled 5 (FZD5) is expressed specifically in immature hMSCs. The FZD5 cell surface antigen was also highly expressed in the primary MSC fraction (LNGFR+ THY-1+ ) and cultured MSCs. Treatment of cells with the FZD5 ligand WNT5A promoted their proliferation. Upon FZD5 knockdown, hMSCs exhibited markedly attenuated proliferation and differentiation ability. The observed increase in the levels of senescence markers suggested that FZD5 knockdown promotes cellular senescence by regulating the noncanonical Wnt pathway. Conversely, FZD5 overexpression delayed cell cycle arrest during the continued culture of hMSCs. These results indicated that the intrinsic activation of FZD5 plays an essential role in negatively regulating senescence in hMSCs and suggested that controlling FZD5 signaling offers the potential to regulate hMSC quality and improve the efficacy of cell-replacement therapies using hMSCs.