Generation of male germ cells from induced pluripotent stem cells （iPS cells）： an in vitro and in vivo study

Recent studies have reported that induced pluripotent stem （iPS） cells from mice and humans can differentiate into primordial germ cells. However, whether iPS cells are capable of producing male germ cells is not known. The objective of this study was to investigate the differentiation potential of mouse iPS cells into spermatogonial stem cells and late-stage male germ cells. We used an approach that combines in vitrodifferentiation and in vivotransplantation. Embryoid bodies （EBs） were obtained from iPS cells using leukaemia inhibitor factor （LIF）-free medium. Quantitative PCR revealed a decrease in Oct4 expression and an increase in StraSand Vasa mRNA in the EBs derived from iPS cells, iPS cell-derived EBs were induced by retinoic acid to differentiate into spermatogonial stem cells （SSCs）, as evidenced by their expression of VASA, as well as CDH1 and GFRal, which are markers of SSCs. Furthermore, these germ cells derived from iPS cells were transplanted into recipient testes of mice that had been pre-treated with busulfan. Notably, iPS cell-derived SSCs were able to differentiate into male germ cells ranging from spermatogonia to round spermatids, as shown by VASA and SCP3 expression. This study demonstrates that iPS cells have the potential to differentiate into late-stage male germ cells. The derivation of male germ cells from iPS cells has potential applications in the treatment of male infertility and provides a model for uncovering the molecular mechanisms underlying male germ cell development.

Derivation of male germ cells from induced pluripotent stem （iPS） cells： a novel and crucial source for generating male gametes

One of the most significant findings in recent stem cell research is the establishment of the induced pluripotent stem （iPS） cells, because they could have critical implications in both regenerative and repro- ductive medicine. Male gametes play a crucial role in transmitting genetic information to subsequent generations, and notably there are more and more patients with azoospermia, due to genetic and environmental factors. Recent advancements on generation of male gametes from human iPS cells would bring great promise to produce patient own male gametes for treating male infertility and provide an excellent platform for unveiling molecular mechanisms of male germ cell development.

Bioengineered skin organoids:from development to applications

Signifcant advancements have been made in recent years in the development of highly sophisticated skin organoids.Serving as three-dimensional(3D)models that mimic human skin,these organoids have evolved into complex structures and are increasingly recognized as efective alternatives to traditional culture models and human skin due to their ability to overcome the limitations of two-dimensional(2D)systems and ethical concerns.The inherent plasticity of skin organoids allows for their construction into physiological and pathological models,enabling the study of skin development and dynamic changes.This review provides an overview of the pivotal work in the progression from 3D layered epidermis to cyst-like skin organoids with appendages.Furthermore,it highlights the latest advancements in organoid construction facilitated by state-of-the-art engineering techniques,such as 3D printing and microfuidic devices.The review also summarizes and discusses the diverse applications of skin organoids in developmental biology,disease modelling,regenerative medicine,and personalized medicine,while considering their prospects and limitations.

Vitamin E in the management of pancreatic cancer: A scoping review

Pancreatic cancer is the leading cause of cancer mortality worldwide.Research investigating effective management strategies for pancreatic cancer is ongoing.Vitamin E,consisting of both tocopherol and tocotrienol,has demonstrated debatable effects on pancreatic cancer cells.Therefore,this scoping review aims to summarize the effects of vitamin E on pancreatic cancer.In October 2022,a literature search was conducted using PubMed and Scopus since their inception.Original studies on the effects of vitamin E on pancreatic cancer,including cell cultures,animal models and human clinical trials,were considered for this review.The literature search found 75 articles on this topic,but only 24 articles met the inclusion criteria.The available evidence showed that vitamin E modulated proliferation,cell death,angiogenesis,metastasis and inflammation in pancreatic cancer cells.However,the safety and bioavailability concerns remain to be answered with more extensive preclinical and clinical studies.More in-depth analysis is necessary to investigate further the role of vitamin E in the management of pancreatic cancers.

Targeting ferroptosis suppresses osteocyte glucolipotoxicity and alleviates diabetic osteoporosis

Diabetic osteoporosis(DOP) is the leading complication continuously threatening the bone health of patients with diabetes. A key pathogenic factor in DOP is loss of osteocyte viability. However, the mechanism of osteocyte death remains unclear. Here, we identified ferroptosis, which is iron-dependent programmed cell death, as a critical mechanism of osteocyte death in murine models of DOP. The diabetic microenvironment significantly enhanced osteocyte ferroptosis in vitro, as shown by the substantial lipid peroxidation, iron overload, and aberrant activation of the ferroptosis pathway. RNA sequencing showed that heme oxygenase-1(HO-1) expression was notably upregulated in ferroptotic osteocytes. Further findings revealed that HO-1 was essential for osteocyte ferroptosis in DOP and that its promoter activity was controlled by the interaction between the upstream NRF2 and c-JUN transcription factors. Targeting ferroptosis or HO-1 efficiently rescued osteocyte death in DOP by disrupting the vicious cycle between lipid peroxidation and HO-1 activation, eventually ameliorating trabecular deterioration. Our study provides insight into DOP pathogenesis, and our results provide a mechanism-based strategy for clinical DOP treatment.

Plasticity of male germline stem cells and their applications in reproductive and regenerative medicine

Spermatogonial stem cells （SSCs）, also known as male germline stem cells, are a small subpopulation of type A spermatogonia with the potential of self-renewal to maintain stem cell pool and differentiation into spermatids in mammalian testis. SSCs are previously regarded as the unipotent stem cells since they can only give rise to sperm within the seminiferous tubules. However, this concept has recently been challenged because numerous studies have demonstrated that SSCs cultured with growth factors can acquire pluripotency to become embryonic stem-like cells. The in vivo and in vitro studies from peers and us have clearly revealed that SSCs can directly transdifferentiate into morphologic, phenotypic, and functional cells of other lineages. Direct conversion to the cells of other tissues has important significance for regenerative medicine. SSCs from azoospermia patients could be induced to differentiate into spermatids with fertilization and developmental potentials. As such, SSCs could have significant applications in both reproductive and regenerative medicine due to their unique and great potentials. In this review, we address the important plasticity of SSCs, with focuses on their self-renewal, differentiation, dedifferentiation, transdifferentiation, and translational medicine studies.

Characterization, isolation, and culture of spermatogonial stem cells in Macaca fascicularis

Spermatogonial stem cells(SSCs)have great applications in both reproductive and regenerative medicine.Primates including monkeys are very similar to humans with regard to physiology and pathology.Nevertheless,little is known about the isolation,the characteristics,and the culture of primate SSCs.This study was designed to identify,isolate,and culture monkey SSCs.Immunocytochemistry was used to identify markers for monkey SSCs.Glial cell line-derived neurotrophic factor family receptor alpha-1(GFRAl)-enriched spermatogonia were isolated from monkeys,namely Macaca fascicularis(M.fascicularis),by two-step enzymatic digestion and magnetic-activated cell sorting,and they were cultured on precoated plates in the conditioned medium.Reverse transcription-polymerase chain reaction(RT-PCR),immunocytochemistry,and RNA sequencing were used to compare phenotype and transcriptomes in GFRAl-enriched spermatogonia between 0 day and 14 days of culture,and xenotransplantation was performed to evaluate the function of GFRAl-enriched spermatogonia.SSCs shared some phenotypes with rodent and human SSCs.GFRAl-enriched spermatogonia with high purity and viability were isolated from M.fascicularis testes.The freshly isolated cells expressed numerous markers for rodent SSCs,and they were cultured for 14 days.The expression of numerous SSC markers was maintained during the cultivation of GFRAl-enriched spermatogonia.RNA sequencing reflected a 97.3%similarity in global gene profiles between 0 day and 14 days of culture.The xenotransplantation assay indicated that the GFRAl-enriched spermatogonia formed colonies and proliferated in vivo in the recipient c-Kitw/w(W)mutant mice.Collectively,GFRAl-enriched spermatogonia are monkey SSCs phenotypically both in vitro and in vivo.This study suggests that monkey might provide an alternative to human SSCs for basic research and application in human diseases.

Targeting pancreatic cancer immune evasion by inhibiting histone deacetylases

The immune system plays a vital role in maintaining the delicate balance between immune recognition and tumor development.Regardless,it is not uncommon that cancerous cells can intelligently acquire abilities to bypass the antitumor immune responses,thus allowing continuous tumor growth and development.Immune evasion has emerged as a significant factor contributing to the progression and immune resistance of pancreatic cancer.Compared with other cancers,pancreatic cancer has a tumor microenvironment that can resist most treatment modalities,including emerging immunotherapy.Sadly,the use of immunotherapy has yet to bring significant clinical breakthrough among pancreatic cancer patients,suggesting that pancreatic cancer has successfully evaded immunomodulation.In this review,we summarize the impact of genetic alteration and epigenetic modification(especially histone deacetylases,HDAC)on immune evasion in pancreatic cancer.HDAC overexpression significantly suppresses tumor suppressor genes,contributing to tumor growth and progression.We review the evidence on HDAC inhibitors in tumor eradication,improving T cells activation,restoring tumor immunogenicity,and modulating programmed death 1 interaction.We provide our perspective in targeting HDAC as a strategy to reverse immune evasion in pancreatic cancer.

PUMA facilitates EMI 1-promoted cytoplasmic Rad51 ubiquitination and inhibits DNA repair in stem and progenitor cells

Maintenance of genetic stability via proper DNA repair in stem and progenitor cells is essential for the tissue repair and regeneration,while preventing cell transformation after damage.Loss of PUMA dramatically increases the survival of mice after exposure to a lethal dose of ionizing radiation(IR),while without promoting tumorigenesis in the long-term survivors.This finding suggests that PUMA(p53 upregulated modulator of apoptosis)may have a function other than regulates apoptosis.Here,we identify a novel role of PUMA in regulation of DNA repair in embryonic or induced pluripotent stem cells(PSCs)and immortalized hematopoietic progenitor cells(HPCs)after IR.We found that PUMA-deficient PSCs and HPCs exhibited a significant higher doublestrand break(DSB)DNA repair activity via Rad51-mediated homologous recombination(HR).This is because PUMA can be associated with early mitotic Inhibitor 1(EMI1)and Rad51 in the cytoplasm to facilitate EMI1-mediated cytoplasmic Rad51 ubiquitination and degradation,thereby inhibiting Rad51 nuclear translocation and HR DNA repair.Our data demonstrate that PUMA acts as a repressor for DSB DNA repair and thus offers a new rationale for therapeutic targeting of PUMA in regenerative cells in the context of DNA damage.

Aging hallmarks of the primate ovary revealed by spatiotemporal transcriptomics

The ovary is indispensable for female reproduction,and its age-dependent functional decline is the primary cause of infertility.However,the molecular basis of ovarian aging in higher vertebrates remains poorly understood.Herein,we apply spatiotemporal transcriptomics to benchmark architecture organization as well as cellular and molecular determinants in young primate ovaries and compare these to aged primate ovaries.From a global view,somatic cells within the non-follicle region undergo more pronounced transcriptional fluctuation relative to those in the follicle region,likely constituting a hostile microenvironment that facilitates ovarian aging.Further,we uncovered that inflammation,the senescent-associated secretory phenotype,senescence,and fibrosis are the likely primary contributors to ovarian aging(PCOA).Of note,we identified spatial co-localization between a PCOA-featured spot and an unappreciated MT2(Metallothionein 2)highly expressing spot(MT2^(high))characterized by high levels of inflammation,potentially serving as an aging hotspot in the primate ovary.Moreover,with advanced age,a subpopulation of MT2^(high)accumulates,likely disseminating and amplifying the senescent signal outward.Our study establishes the first primate spatiotemporal transcriptomic atlas,advancing our understanding of mechanistic determinants underpinning primate ovarian aging and unraveling potential biomarkers and therapeutic targets for aging and age-associated human ovarian disorders.

Ginsenoside Rb1 inhibits oxidative stress-induced ovarian granulosa cell injury through Akt-FoxO1 interaction

Ginsenoside Rb1 shows a strong antioxidant effect and has potential activation effects on Akt.The aim of the present study was to investigate the protective effect of Rb1 on age-related ovarian granulosa cell injury.Ovarian granulosa cells(GCs)were obtained from 50 young women(≤30 years)and 50 aged women(≥38 years)at an IVF center.Young and aged ICR mice were administered with or without Rb1(10 mg kg^(-1),i.p.)for 2 weeks.The protective effects of Rb1 were investigated and the role of Rb1 on the modulation of Akt-FoxO1 interaction was determined with immunofluorescence,Western blotting,immunoprecipitation,si RNA silencing and pharmacological inhibitor.Rb1 effectively decreased LDH and MDA,and reversed the apoptotic-related protein levels in h GL cells from old patients.Similar results were found in mice.In addition,the mitochondrial membrane potential was restored and the overaccumulation of ROS was reversed by Rb1.Rb1 preserved peroxide-impaired Akt activation,to some extent,by increasing phosphorylation at Ser473.Rb1 also facilitated p-Akt binding to FoxO1 and promoted the phosphorylation of FoxO1.Si RNA silencing of Akt,Akt inhibitor LY294002,and FoxO1 inhibitor AS1842856 attenuated the effects of Rb1.Ginsenoside Rb1 inhibits age-related GCs oxidative damage by activating Akt phosphorylation at Ser473 and by further interaction with FoxO1.

NODAL secreted by male germ cells regulates the proliferation and function of human Sertoli cells from obstructive azoospermia and nonobstructive azoospermia patients

This study was designed to explore the regulatory effects of male germ cell secreting factor NODAL on Sertoli cell fate decisions from obstructive azoospermia （OA） and nonobstructive azoospermia （NOA） patients. Human Sertoli cells and male germ cells were isolated using two-step enzymatic digestion and SATPUT from testes of azoospermia patients. Expression of NODAL and its multiple receptors in human Sertoli cells and male germ cells were characterized by reverse transcription-polymerase chain reaction （RT-PCRI and immunochemistry. Human recombinant NODAL and its receptor inhibitor SB431542 were employed to probe their effect on the proliferation of Sertoli cells using the CCK-8 assay. Quantitative PCR and Western blots were utilized to assess the expression of Sertoli cell functional genes and proteins. NODAL was found to be expressed in male germ cells but not in Sertoli cells, whereas its receptors ALK4, ALK7, and ACTR-IIB were detected in Sertoli cells and germ cells, suggesting that NODAL plays a regulatory role in Sertoli cells and germ cells via a paracrine and autocrine pathway, respectively. Human recombinant NODAL could promote the proliferation of human Sertoli cells. The expression of cell cycle regulators, including CYCLIN A, CYCLIN D1 and CYCLIN E, was not remarkably affected by NODAL signaling. NODAL enhanced the expression of essential growth factors, including GDNF, SCF, and BMP4, whereas SB431542 decreased their levels. There was not homogeneity of genes changes by NODAL treatment in Sertoli cells from OA and Sertoli cell-only syndrome （SCO） patients. Collectively, this study demonstrates that NODAL produced by human male germ cells regulates proliferation and numerous gene expression of Sertoli cells.

Non-catalytic roles for TET1 protein negatively regulating neuronal differentiation through srGAP3 in neuroblastoma cells

The methylcytosine dioxygenases TET proteins （TET1, TET2, and TET3） play important regulatory roles in neural function. In this study, we investigated the role of TET proteins in neuronal differentiation using Neuro2a cells as a model. We observed that knockdown of TET1, TET2 or TET3 promoted neuronal differentiation of Neuro2a cells, and their overexpression inhibited VPA （valproic acid）-induced neuronal differentiation, suggesting all three TET proteins negatively regulate neu- ronal differentiation of Neuro2a cells. Interestingly, the inducing activity of TET protein is independent of its enzymatic activity. Our previous studies have demon- strated that srGAP3 can negatively regulate neuronal differentiation of Neuro2a cells. Furthermore, we revealed that TET1 could positively regulate srGAP3 expression independent of its catalytic activity, and srGAP3 is required for TET-mediated neuronal differentiation of Neuro2a cells. The results presented here may facilitate better understanding of the role of TET proteins in neuronal differentiation, and provide a possible therapy target for neuroblastoma.

Single-nucleus profiling unveils a geroprotective role of the Foxo3 in primate skeletal muscle aging

Age-dependent loss of skeletal muscle mass and function is a feature of sarcopenia,and increases the risk of many aging-related metabolic diseases.Here,we report phenotypic and single-nucleus transcriptomic analyses of non-human primate skeletal muscle aging.A higher transcriptional fluctuation was observed in myonuclei relative to other interstitial cell types,indicating a higher susceptibility of skeletal muscle fiber to aging.We found a downregulation of Foxo3 in aged primate skeletal muscle,and identi-fied FOxo3 as a hub transcription factor maintaining skeletal muscle homeostasis.Through the establishment of a complementary experimental pipeline based on a human pluripotent stem cell-derived myotube model,we revealed that silence of Foxo3 accelerates human myotube senescence,whereas genetic activation of endogenous FOxO3 alleviates human myotube aging.Altogether,based on a combination of monkey skeletal muscle and human myotube aging research models,we unraveled the pivotal role of the FOxO3 in safeguarding primate skeletal muscle from aging,providing a comprehensive resource for the development of clinical diagnosis and targeted therapeutic interventions against human skeletal muscle aging and the onset of sarcopenia along with aging-relateddisorders.

PRPS2 mutations drive acute lymphoblastic leukemia relapse through influencing PRPS1/2 hexamer stability

Tumor relapse is the major cause of treatment failure in childhood acute lymphoblastic leukemia(ALL),yet the underlying mechanisms are still elusive.Here,we demonstrate that phosphoribosyl pyrophosphate synthetase 2(PRPS2)mutations drive ALL relapse through influencing PRPS1/2 hexamer stability.Ultra-deep sequencing was performed to identify PRPS2 mutations in ALL samples.The effects of PRPS2 mutations on cell survival,cell apoptosis,and drug resistance were evaluated.In vitro PRPS2 enzyme activity and ADP/GDP feedback inhibition of PRPS enzyme activity were assessed.Purine metabolites were analyzed by ultra-performance liquid-chromatography tandem mass spectrometry(UPLC–MS/MS).Integrating sequencing data with clinical information,we identified PRPS2 mutations only in relapsed childhood ALL with thiopurine therapy.Functional PRPS2 mutations mediated purine metabolism specifically on thiopurine treatment by influencing PRPS1/2 hexamer stability,leading to reduced nucleotide feedback inhibition of PRPS activity and enhanced thiopurine resistance.The 3-amino acid V103-G104-E105,the key difference between PRPS1 and PRPS2,insertion in PRPS2 caused severe steric clash to the interface of PRPS hexamer,leading to its low enzyme activity.In addition,we demonstrated that PRPS2 P173R increased thiopurine resistance in xenograft models.Our work describes a novel mechanism by which PRPS2 mutants drive childhood ALL relapse and highlights PRPS2 mutations as biomarkers for relapsed childhood ALL.

Sirtuin Functions in the Brain:From Physiological to Pathological Aspects

Sirtuins are a family of nicotinamide adenine dinucleotide(NAD+) dependent deacetylases involved in multiple biological functions including metabolism, inflammation, stress resistance and aging. In mammals,there are seven members(Sirt1—Sirt7), with diversities in their subcellular localizations and enzymatic activities.Here, we review the functions of sirtuins, with a focus on their roles in normal brain physiology such as neural development regulation, body homeostasis maintenance, and memory formation. We also discuss the role of sirtuins in a variety of brain diseases including stroke, Alzheimer's, Parkinson's, and motor neuron dysfunction.Because of the emerging functions of sirtuins in brain physiology and pathology, drugs targeting sirtuins may offer potential therapeutic values for brain disorders.

Multi-omics analysis based on 3D-bioprinted models innovates therapeutic target discovery of osteosarcoma

Current in vitro models for osteosarcoma investigation and drug screening,including two-dimensional(2D)cell culture and tumour spheroids(i.e.cancer stem-like cells),lack extracellular matrix(ECM).Therefore,results from traditional models may not reflect real pathological processes in genuine osteosarcoma histological structures.Here,we report a three-dimensional(3D)bioprinted osteosarcoma model(3DBPO)that contains osteosarcoma cells and shrouding ECM analogue in a 3D frame.Photo-crosslinkable bioinks composed of gelatine methacrylamide and hyaluronic acid methacrylate mimicked tumour ECM.We performed multi-omics analysis,including transcriptomics and DNA methylomics,to determine differences between the 3DBPO model and traditional models.Compared with 2D models and tumour spheroids,our 3DBPO model showed significant changes in cell cycle,metabolism,adherens junctions,and other pathways associated with epigenetic regulation.The 3DBPO model was more sensitive to therapies targeted to the autophagy pathway.We showed that simulating ECM yielded different osteosarcoma cell metabolic characteristics and drug sensitivity in the 3DBPO model compared with classical models.We suggest 3D printed osteosarcoma models can be used in osteosarcoma fundamental and translational research,which may contribute to novel therapeutic strategy discovery.