Rate, Risk Factors, and Outcomes of Invasive Fungal Infections in Patients with Hematologic Malignancies.

Background: Invasive fungal infections (IFIs) are a significant cause of mortality and morbidity in patients with hematological malignancies. Given the considerable prevalence and consequences of IFIs, hence revealing the exact cause of fungal infections, their rate, associated risk factors, and complications could contribute to reducing both financial and life costs, choosing targeted antifungal treatment, and avoiding unnecessary toxic treatments in individuals who are not suffering from mycoses. Materials and Methods: This prospective cross-sectional study was conducted in the first semester of 2019. All patients with hematologic malignancies (HM) admitted to Dr. Shariati Hospital were studied. Only those with probable/proven IFIs defined according to the last update of EORTC/MSG criteria were included in the study. The demographic and clinical data were recorded from the hospital information registration system using a questionnaire. Statistical analysis was performed using SPSS software version 24. Results: Out of 1109 HM patients hospitalized during the study period, 67 (6.04%) IFIs were diagnosed. Of these, 57 (85.04%) were aspergillosis, 7 (10.4%) were mucormycosis, and 3 patients developed other fungal infections. Males constituted 67.2% of the entire IFI population. The mean±SD age of the samples was 43.16 ± 13.8 years. The most common type of malignancy was AML. Lung imaging showed lesions associated with fungal infections in 52 cases (77.6%), with multiple nodules as the most prevalent pattern being observed in 64.2% of cases. Sinus involvement was evidenced in the PNS CT scan of 46 (68.6%) patients. The attributable mortality rate for IFIs was 62.7%. Both the types of IFI and malignancies had no significant relationship with the outcome of patients. Central venous catheter, mucositis, and antibiotic use were the most frequent risk factors. Conclusion:  IFI represents a frequent complication for HM patients with high mortality. Aspergillus species are the predominant etiology in these settings. Considering our results, in high-risk patients, manifestations of warning signs in the sinus and lungs, which would not be cleared despite receiving antibiotics, should raise the possibility of IFIs.

Applications of single-cell omics for chimeric antigen receptor T cell therapy.

Chimeric antigen receptor (CAR) T cell therapy is a promising cancer treatment modality. The breakthroughs in CAR T cell therapy were, in part, possible with the help of cell analysis methods, such as single-cell analysis. Bulk analyses have provided invaluable information regarding the complex molecular dynamics of CAR T cells, but their results are an average of thousands of signals in CAR T or tumour cells. Since cancer is a heterogeneous disease where each minute detail of a subclone could change the outcome of the treatment, single-cell analysis could prove to be a powerful instrument in deciphering the secrets of tumour microenvironment for cancer immunotherapy. With the recent studies in all aspects of adoptive cell therapy making use of single-cell analysis, a comprehensive review of the recent preclinical and clinical findings in CAR T cell therapy was needed. Here, we categorized and summarized the key points of the studies in which single-cell analysis provided insights into the genomics, epigenomics, transcriptomics and proteomics as well as their respective multi-omics of CAR T cell therapy.

Evaluation of Inflammatory Markers in Patients with Depressed Episodes in Major Depressive Disorder and Bipolar Disorder before and after Treatment.

Depression is one of the current dilemmas in both developed and developing societies. Studies show that the severity of psychiatric symptoms is directly related to the degree of inflammation caused by cytokines secreted by the immune system. Hence, evaluating serum cytokine levels in patients with depression can help to understand the pathogenesis of the disease and make the best therapeutic decisions. The present study investigated the levels of inflammatory cytokines, tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), and interleukin-6 (IL-6) in patients with major depression or bipolar disorder during depressive episodes (BDDE) before and after a 6-month pharmaceutical intervention. Patients referring to 3 clinics were recruited for the study. The diagnosis of major depression or bipolar disorder in a depressive phase was made according to the Diagnostic and Statistical Manual of Mental Disorders -5(DSM-5) criteria. There was a significant difference in depression levels between the pre-intervention and 6-month follow-up in both groups. After 6 months, IL-1 and IL-6 levels in the bipolar disorder group had decreased while TNF-α levels had increased. There was also a significant difference between pre-intervention and follow-up levels of IL-1.  Serum levels of IL-1 and IL-6 decreased significantly in both groups after the 6-month follow-up, and symptom improvement was observed. TNF-α levels, on the other hand, decreased in the major depression group but increased in the bipolar disorder group. Considering that inflammation is a major outcome of depression, treatment strategies to reduce inflammation could be a practical approach to improving psychiatric symptoms.

Advances in natural killer cell therapies for breast cancer.

Breast cancer (BC) is the most common cause of cancer death in women. According to the American Cancer Society's yearly cancer statistics, BC constituted almost 15% of all the newly diagnosed cancer cases in 2022 for both sexes. Metastatic disease occurs in 30% of patients with BC. The currently available treatments fail to cure metastatic BC, and the average survival time for patients with metastatic BC is approximately 2 years. Developing a treatment method that terminates cancer stem cells without harming healthy cells is the primary objective of novel therapeutics. Adoptive cell therapy is a branch of cancer immunotherapy that utilizes the immune cells to attack cancer cells. Natural killer (NK) cells are an essential component of innate immunity and are critical in destroying tumor cells without prior stimulation with antigens. With the advent of chimeric antigen receptors (CARs), the autologous or allogeneic use of NK/CAR-NK cell therapy has raised new hopes for treating patients with cancer. Here, we describe recent developments in NK and CAR-NK cell immunotherapy, including the biology and function of NK cells, clinical trials, different sources of NK cells and their future perspectives on BC.

Wharton's jelly-mesenchymal stem cells treatment for severe COVID 19 patients: 1-year follow-up.

Background: Recently, attention has been focused on mesenchymal stem cells (MSC) because of their unique ability to suppress inflammation induced by cytokine storms caused by COVID-19. Several patients have been successfully treated in this manner. After one year of treatment with Wharton's jelly-derived MSC injections, this study evaluated the safety and efficacy of injecting MSCs intravenously in patients with COVID-19. Methods: This study treated four patients with severe COVID-19 with Wharton's jelly-derived mesenchymal stem cells. In this study, patients were followed up for routine tests, tumor markers, and whole-body imaging (spiral neck CT scan (with contrast), spiral chest CT scan (with & without contrast), and spiral abdominopelvic CT scan (with IV & Oral contrast)) one year after cell therapy. Results: The results indicated that lymphocyte; lymph count significantly increased, and neutrophil, ESR, ferritin, and CRP significantly decreased. LDH showed a non-significant decrease (P-value<0.05). One year after the WJ-MSC injection, the tumor markers were normal, and no tumors were observed in patients after one year. Also, the CT scan result was normal. Conclusions: In patients, no serious complications were observed after a one-year follow-up. After monitoring the patient via laboratory tests, tumor markers, and whole-body imaging, we concluded that the Wharton jelly-derived mesenchymal stem cells did not cause severe complications, including tumor formation, in severe COVID19 patients within a year. More clinical trials with higher sample sizes need to be performed on cell therapy with Wharton jelly-derived mesenchymal stem cells in the future.

Mesenchymal Stem Cells Regenerate Diabetic Foot Ulcers: A Review Article.

Background: Diabetes is one of the metabolic diseases characterized by hyperglycemia, with many complications. Diabetic foot ulcer (DFU) is a significant complication of diabetes. Various therapy procedures have been recently described for DFU improvement. Methods: Using PubMed, Scopus, Science Direct, and Google Scholar to discover the therapeutic effects of bee products, this review study was conducted in 2018-2019 by searching PubMed, Scopus, Science Direct, and Google Scholar databases. Results: Cell therapies with various cell candidates such as mesenchymal stem cells (MSCs) are increasingly introduced into routine medical care to manage skin wounds. The applying of these cells for tissue regeneration was initially based on the capability of MSCs to differentiate into specialized cells within the injured tissue. Paracrine signaling and differentiation mechanisms have both been contributed to improving tissue repair by MCSs. However, the role of MSCs differentiation is less due to the poor survival of these cells at the site of injury. Conclusion: At the same time, paracrine signaling or their secretome is the primary mechanism of MSCs that stimulate neovascularization and re-epithelialization and mobilization of inhabitant stem cells. In this review study, we discuss the role of MSCs and their secretome that can improve the use of this new approach in treating ulcers and DFU.

Patient-derived xenograft (PDX) models, applications and challenges in cancer research.

The establishing of the first cancer models created a new perspective on the identification and evaluation of new anti-cancer therapies in preclinical studies. Patient-derived xenograft models are created by tumor tissue engraftment. These models accurately represent the biology and heterogeneity of different cancers and recapitulate tumor microenvironment. These features have made it a reliable model along with the development of humanized models. Therefore, they are used in many studies, such as the development of anti-cancer drugs, co-clinical trials, personalized medicine, immunotherapy, and PDX biobanks. This review summarizes patient-derived xenograft models development procedures, drug development applications in various cancers, challenges and limitations.

Mesenchymal stem cells and natural killer cells interaction mechanisms and potential clinical applications.

Natural killer cells (NK cells) are innate immune cells that are activated to fight tumor cells and virus-infected cells. NK cells also play an important role in the graft versus leukemia response. However, they can over-develop inflammatory reactions by secreting inflammatory cytokines and increasing Th1 differentiation, eventually leading to tissue damage. Today, researchers have attributed some autoimmune diseases and GVHD to NK cells. On the other hand, it has been shown that mesenchymal stem cells (MSCs) can modulate the activity of NK cells, while some researchers have shown that NK cells can cause MSCs to lysis. Therefore, we considered it is necessary to investigate the effect of these two cells and their signaling pathway in contact with each other, also their clinical applications.

Application of Wharton jelly-derived mesenchymal stem cells in patients with pulmonary fibrosis.

Pulmonary fibrosis is a devastating disease that eventually leads to death and respiratory failure. Despite the wide range of drugs, including corticosteroids, endothelin antagonist, and pirfenidone, there is no effective treatment, and the only main goal of treatment is to alleviate the symptoms as much as possible to slow down the progression of the disease and improve the quality of life. Lung transplantation may be a treatment option for a few people if pulmonary fibrosis develops and there is no established treatment. Pulmonary fibrosis caused by the COVID19 virus is another problem that we face in most patients despite the efforts of the international medical communities. Therefore, achieving alternative treatment for patients is a great success. Today, basic research using stem cells on pulmonary fibrosis has published promising results. New stem cell-based therapies can be helpful in patients with pulmonary fibrosis. Wharton jelly-derived mesenchymal stem cells are easily isolated in large quantities and made available for clinical trials without causing ethical problems. These cells have higher flexibility and proliferation potential than other cells isolated from different sources and differentiated into various cells in laboratory environments. More clinical trials are needed to determine the safety and efficacy of these cells. This study will investigate the cellular and molecular mechanisms and possible effects of Wharton jelly-derived mesenchymal stem cells in pulmonary fibrosis.

Development and Clinical Application of Tumor-derived Exosomes in Patients with Cancer.

A tumor is an abnormal growth of cells within a tissue that can lead to death due to late diagnosis, poor prognosis, drug resistance, and finally enhanced metastasis formation. Exosomes are nanovesicles that have been derived from all the different cell types. These vesicles can transfer various molecules, including the distinct form of nucleic acids (mRNA, miRNA, and circRNA) and proteins. Tumor-derived exosomes (TEXs) have exceptionally important roles through multiple molecular and cellular pathways like progression, tumorigenesis, drug resistance, and as well as metastasis. TEXs are detectable in all body fluids such as serum and urine, a convenient and non-invasive way to access these nano-sized vesicles. TEXs lead to the symptom expression of genetic aberrations in the tumor cell population, making them an accurate and sensitive biomarker for the diagnosis and prognosis of tumors. On the other hand, TEXs contain major histocompatibility complexes (MHCs) and play important dual roles in regulating tumor immune responses: they can mediate both immune activation and suppression through tumor-associated immunity. Despite numerous scientific studies, there are still many technical barriers to distinguish TEXs from non-tumor-derived exosomes. Even so, removing exosomes leading to a wide difference in outcomes inside a patient's body. Hence, controversial pieces of evidence have demonstrated the vital role of TEXs as hopeful biomarkers for the early detection of cancers, evaluation of therapeutic effects, and monitoring of the patient.

Therapeutic approach of adipose-derived mesenchymal stem cells in refractory peptic ulcer.

Peptic ulcer is one of the most common gastrointestinal tract disorders worldwide, associated with challenges such as refractory morbidity, bleeding, interference with use of anticoagulants, and potential side effects associated with long-term use of proton pump inhibitors. A peptic ulcer is a defect in gastric or duodenal mucosa extending from muscularis mucosa to deeper layers of the stomach wall. In most cases, ulcers respond to standard treatments. However, in some people, peptic ulcer becomes resistant to conventional treatment or recurs after initially successful therapy. Therefore, new and safe treatments, including the use of stem cells, are highly favored for these patients. Adipose-derived mesenchymal stem cells are readily available in large quantities with minimal invasive intervention, and isolation of adipose-derived mesenchymal stromal stem cells (ASC) produces large amounts of stem cells, which are essential for cell-based and restorative therapies. These cells have high flexibility and can differentiate into several types of cells in vitro. This article will investigate the effects and possible mechanisms and signaling pathways of adipose tissue-derived mesenchymal stem cells in patients with refractory peptic ulcers.

Clinical and laboratory findings and PCR results in severe and non-severe COVID19 patients based on CURB-65 and WHO severity indices.

BACKGROUND: The importance of clinicolaboratory characteristics of COVID-19 made us report our findings in the Alborz province according to the latest National Guideline for the diagnosis and treatment of COVID-19 in outpatients and inpatients (trial five versions, 25 March 2020) of Iran by emphasizing rRT-PCR results, clinical features, comorbidities, and other laboratory findings in patients according to the severity of the disease. METHODS: In this study, 202 patients were included, primarily of whom 164 had fulfilled the inclusion criteria. This cross-sectional, two-center study that involved 164 symptomatic adults hospitalized with the diagnosis of COVID-19 between March 5 and April 5, 2020, was performed to analyze the frequency of rRT-PCR results, distribution of comorbidities, and initial clinicolaboratory data in severe and non-severe cases, comparing the compatibility of two methods for categorizing the severity of the disease. RESULTS: According to our findings, 111 patients were rRT-PCR positive (67.6%), and 53 were rRT-PCR negative (32.4%), indicating no significant difference between severity groups that were not related to the date of symptoms' onset before admission. Based on the National Guideline, among vital signs and symptoms, mean oxygen saturation and frequency of nausea showed a significant difference between the two groups (P < 0.05); however, no significant difference was observed in comorbidities. In CURB-65 groups, among vital signs and comorbidities, mean oxygen saturation, diabetes, hypertension (HTN), hyperlipidemia, chronic heart disease (CHD), and asthma showed a significant difference between the two groups (P < 0.05), but no significant difference was seen in symptoms. CONCLUSION: In this study, rRT-PCR results of hospitalized patients with COVID-19 were not related to severity categories. From initial clinical characteristics, decreased oxygen saturation appears to be a more common abnormality in severe and non-severe categories. National Guideline indices seem to be more comprehensive to categorize patients in severity groups than CURB-65, and there was compatibility just in non-severe groups of National Guideline and CURB-65 categories.

Cell therapy in patients with COVID-19 using Wharton's jelly mesenchymal stem cells: a phase 1 clinical trial.

BACKGROUND: Mesenchymal stem cells (MSCs) have received particular attention because of their ability to modulate the immune system and inhibit inflammation caused by cytokine storms due to SARS-CoV-2. New alternative therapies may reduce mortality rates in patients with COVID19. This study aimed to assess the safety and efficacy of injecting intravenous Wharton's jelly-derived MSCs in patients with COVID-19 as a treatment. METHODS: In this study, five patients with severe COVID-19 were treated with Wharton's jelly-derived mesenchymal stem cells (150 × 106 cells per injection). These patients were subject to three intravenous injections 3 days apart, and monitoring was done on days 0, 3, 6, and 14 in routine tests, inflammatory cytokines, and flow cytometry of CD4 and CD8 markers. A lung CT scan was performed on base and days 14 and 28. In addition, IgM and IgG antibodies against SARS-CoV-2 were measured before and after treatment. RESULTS: The results showed that IL-10 and SDF-1 increased after cell therapy, but VEGF, TGF-ß, IFN-γ, IL-6, and TNFα decreased. Routine hematology tests, myocardial enzyme tests, biochemical tests, and inflammation tests were performed for all patients before and after cell therapy on base and days 3, 6, and 14, which indicated the improvement of test results over time. COVID-19 antibody tests rose in 14 days after WJ-MSC injection. The total score of zonal involvement in both lungs was improved. CONCLUSIONS: In patients, the trend of tests was generally improving, and we experienced a reduction in inflammation. No serious complications were observed in patients except the headache in one of them, which was resolved without medication. In this study, we found that patients with severe COVID-19 in the inflammatory phase respond better to cell therapy. More extensive clinical trials should be performed in this regard. TRIAL REGISTRATION: IRCT, IRCT20190717044241N2 . Registered April 22, 2020.

Clinical and laboratory findings in COVID-19 adult hospitalized patients from Alborz province / Iran: comparison of rRT-PCR positive and negative.

BACKGROUND: The novel coronavirus disease 2019 (COVID-19) was emergency turned into global public health after the first patients were detected in Wuhan, China, in December 2019. The disease rapidly expanded and led to an epidemic throughout China, followed by the rising number of cases worldwide. Given the high prevalence of COVID-19, rapid and accurate diagnostic methods are immediately needed to identify, isolate and treat the patients as soon as possible, decreasing mortality rates and the risk of public contamination by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2). METHODS: This case-control study was conducted in two hospitals in Alborz Province in Iran. All recruited cases in this study were symptomatic adults hospitalized as COVID-19 patients with compatible Computed tomographic (CT) scan findings and available rRT-PCR results. The patients were recruited in this study. The patients were categorized into positive and negative rRT-PCR groups and evaluated for symptoms, initial vital signs, comorbidity, clinical and laboratory findings. Finally, the results were assessed by SPSS software. RESULTS: Between March 5 to April 5, 2020, 164 symptomatic COVID-19 patients were studied. In total, there were 111 rRT-PCR positive (67.6%) and 53 rRT-PCR negative patients (32.4%). In terms of statistics, the frequency of symptoms revealed no difference, except for cough (P.V:0.008), dizziness (PV: 0.048), and weakness (P.V:0.022). Among initial vital signs, PR (P.V:0.041) and O2 Saturation (PV: 0.014) were statistically different between the two groups. Evaluation of comorbidities revealed no difference except for hyperlipidemia (P.V:0.024). In the comparison of laboratory findings, only WBC count (PV: 0.001), lymphocyte count (PV: 0.001), and Hb (P.V:0.008) were statistically different between the two groups. CONCLUSION: In case of the negative rRT-PCR result, it is necessary to take a logical approach, and we recommended that the physician decides according to clinical manifestations, laboratory findings, and positive CT results.

The role of mesenchymal stromal cells in immune modulation of COVID-19: focus on cytokine storm.

The outbreak of coronavirus disease 2019 (COVID-19) pandemic is quickly spreading all over the world. This virus, which is called SARS-CoV-2, has infected tens of thousands of people. Based on symptoms, the pathogenesis of acute respiratory illness is responsible for highly homogenous coronaviruses as well as other pathogens. Evidence suggests that high inflammation rates, oxidation, and overwhelming immune response probably contribute to pathology of COVID-19. COVID-19 causes cytokine storm, which subsequently leads to acute respiratory distress syndrome (ARDS), often ending up in the death of patients. Mesenchymal stem cells (MSCs) are multipotential stem cells that are recognized via self-renewal capacity, generation of clonal populations, and multilineage differentiation. MSCs are present in nearly all tissues of the body, playing an essential role in repair and generation of tissues. Furthermore, MSCs have broad immunoregulatory properties through the interaction of immune cells in both innate and adaptive immune systems, leading to immunosuppression of many effector activities. MSCs can reduce the cytokine storm produced by coronavirus infection. In a number of studies, the administration of these cells has been beneficial for COVID-19 patients. Also, MSCs may be able to improve pulmonary fibrosis and lung function. In this review, we will review the newest research findings regarding MSC-based immunomodulation in patients with COVID-19.

Perspective of placenta derived mesenchymal stem cells in acute liver failure.

Acute Liver failure (ALF) is a life-threatening disease and is determined by coagulopathy (with INR ≥ 1.5) and hepatic encephalopathy as a result of severe liver injury in patients without preexisting liver disease. Since there are problems with liver transplantation including lack of donors, use of immunosuppressive drugs, and high costs of this process, new therapeutic approaches alongside current treatments are needed. The placenta is a tissue that is normally discarded after childbirth. On the other hand, human placenta is a rich source of mesenchymal stem cells (MSCs), which is easily available, without moral problems, and its derived cells are less affected by age and environmental factors. Therefore, placenta-derived mesenchymal stem cells (PD-MSCs) can be considered as an allogeneic source for liver disease. Considering the studies on MSCs and their effects on various diseases, it can be stated that MSCs are among the most important agents to be used for novel future therapies of liver diseases. In this paper, we will investigate the effects of mesenchymal stem cells through migration and immigration to the site of injury, cell-to-cell contact, immunomodulatory effects, and secretory factors in ALF.

Inhibitory Effect of Mesenchymal Stem Cell Co-Culture on Erythroid Differentiation of K562 Cells Compared to The Control Group.

OBJECTIVE: Bone marrow mesenchymal stem cells (BMMSCs) reside in the bone marrow and control the process of hematopoiesis. They are an excellent instrument for regenerative treatment and co-culture with hematopoietic stem cells (HSCs). MATERIALS AND METHODS: In this experimental study, K562 cell lines were either treated with butyric acid and co-cultured with MSCs, or cultivated in a conditioned medium from MSCs plus butyric acid for erythroid differentiation. We used the trypan blue dye exclusion assay to determine cell counts and viability in each group. For each group, we separately assessed erythroid differentiation of the K562 cell line with Giemsa stain under light microscopy, expression of specific markers of erythroid cells by flowcytometry, and erythroidspecific gene expressions by real-time polymerase chain reaction (RT-PCR). RESULTS: There was enhandced erythroid differentiation of K562 cells with butyric acid compared to the K562 cell line co-cultured with MSCs and butyric acid. Erythroid differentiation of the K562 cell line cultivated in conditioned medium with butyric acid was higher than the K562 cell line co-cultured with MSCs and butyric acid, but less than K562 cell line treated with butyric acid only. CONCLUSION: Our results showed that MSCs significantly suppressed erythropoiesis. Therefore, MSCs would not be a suitable optimal treatment strategy for patients with erythroid leukemia.

The Effect of Bone Marrow Mesenchymal Stem Cells on Vitamin D3 Induced Monocytic Differentiation of U937 Cells.

PURPOSE: Mesenchymal stem cells (MSCs) are key components of the hematopoietic stem cells (HSCs) niche. They control the process of hematopoiesis by secreting regulatory cytokines, growth factors and expression of important cell adhesion molecules for cell-tocell interactions. In this research, we have investigated the effect of bone marrow derived MSCs on monocytic differentiation of U937 cells line. METHODS: U937 cells were cultured in both direct co-culture with MSCs and MSCs conditioned medium (C.M) driven. This study used 1,25-dihydroxyvitamin D3(VitD3) as inductor of monocytic differentiation and U937 cells treated with VitD3 morphology was examined by Wright Giemsa staining. CD14 monocytic differentiation marker was measured by flow cytometry and monocytic gene expression was assessed by real time polymerase chain reaction (RT PCR). RESULTS: The results of flow cytometric analysis showed that CD14 expression of U937 increased. The higher effect of MSCs co-culture on CD14 expression in U937 cells was observed, compared to the conditioned medium. Among ten monocytic related genes which were screened that was observed increase in 5 genes in which CXCR4 and CSF2RA showed significant increase. CONCLUSION: The results obtained show that MSCs have supportive effect on the monocytic differentiation of U937 cells. However, a distinct mechanism of that remains unclear.

The Impact of Mesenchymal Stem Cells on Differentiation of Hematopoietic Stem Cells.

Bone marrow microenvironment contains cellular and acellular compartments. The cellular compartment includes hematopoietic stem cells, mesenchymal stem cells and some other stromal cell types, while the acellular compartment is composed of scaffold proteins known as the extra cellular matrix. Direct cell-cell contact as well as cytokines secreted by mesenchymal stem cells during coculture of hematopoietic stem cells and mesenchymal stem cells play a critical role in hematopoiesis, and determines the fate of hematopoietic stem cells. Several studies have demonstrated the impact of mesenchymal stem cells on self-renewal, expansion, proliferation and differentiation of hematopoietic stem cells in vitro, which have shown different and contradictory results. In this paper, we will investigate the effect of mesenchymal stem cells on differentiation of hematopoietic stem cells in vitro.

The Effect of Hypoxia on Mesenchymal Stem Cell Biology.

Although physiological and pathological role of hypoxia have been appreciated in mammalians for decades however the cellular biology of hypoxia more clarified in the past 20 years. Discovery of the transcription factor hypoxia-inducible factor (HIF)-1, in the 1990s opened a new window to investigate the mechanisms behind hypoxia. In different cellular contexts HIF-1 activation show variable results by impacting various aspects of cell biology such as cell cycle, apoptosis, differentiation and etc. Mesenchymal stem cells (MSC) are unique cells which take important role in tissue regeneration. They are characterized by self-renewal capacity, multilineage potential, and immunosuppressive property. Like so many kind of cells, hypoxia induces different responses in MSCs by HIF- 1 activation. The activation of this molecule changes the growth, multiplication, differentiation and gene expression profile of MSCs in their niche by a complex of signals. This article briefly discusses the most important effects of hypoxia in growth kinetics, signalling pathways, cytokine secretion profile and expression of chemokine receptors in different conditions.