Reconstruction of hematopoietic inductive microenvironment after transplantation of VCAM-1-modified human umbilical cord blood stromal cells

Soluble factors secreted by human Wharton’s jelly mesenchymal stromal/stem cells exhibit therapeutic radioprotection: A mechanistic study with integrating network biology

BACKGROUND

Human Wharton’s jelly-derived mesenchymal stromal/stem cells (hWJ-MSCs) have gained considerable attention in their applications in cell-based therapy due to several advantages offered by them. Recently, we reported that hWJ-MSCs and their conditioned medium have significant therapeutic radioprotective potential. This finding raised an obvious question to identify unique features of hWJ-MSCs over other sources of stem cells for a better understanding of its radioprotective mechanism.

AIM

To understand the radioprotective mechanism of soluble factors secreted by hWJ-MSCs and identification of their unique genes.

METHODS

Propidium iodide staining, endogenous spleen colony-forming assay, and survival study were carried out for radioprotection studies. Homeostasis-driven proliferation assay was performed for in vivo lymphocyte proliferation. Analysis of RNAseq data was performed to find the unique genes of WJ-MSCs by comparing them with bone marrow mesenchymal stem cells, embryonic stem cells, and human fibroblasts. Gene enrichment analysis and protein-protein interaction network were used for pathway analysis.

RESULTS

Co-culture of irradiated murine splenic lymphocytes with WJ-MSCs offered significant radioprotection to lymphocytes. WJ-MSC transplantation increased the homeostasis-driven proliferation of the lymphocytes. Neutralization of WJ-MSC conditioned medium with granulocyte-colony stimulating factor antibody abolished therapeutic radioprotection. Transcriptome analysis showed that WJ-MSCs share several common genes with bone marrow MSCs and embryonic stem cells and express high levels of unique genes such as interleukin (IL)1-α, IL1-β, IL-6, CXCL3, CXCL5, CXCL8, CXCL2, CCL2, FLT-1, and IL-33. It was also observed that WJ-MSCs preferentially modulate several cellular pathways and processes that handle the repair and regeneration of damaged tissues compared to stem cells from other sources. Cytokine-based network analysis showed that most of the radiosensitive tissues have a more complex network for the elevated cytokines.

CONCLUSION

Systemic infusion of WJ-MSC conditioned media will have significant potential for treating accidental radiation exposed victims.

Effects of Low-Intensity Pulsed Ultrasound on Myelosuppression of Rats Induced by Chemotherapy Drugs With Cell Cycle Specificity

OBJECTIVES

To explore the ameliorating effects of low-intensity pulsed ultrasound (LIPUS) on Sprague Dawley rat myelosuppression induced by cell cycle specificity drugs (docetaxel, mitotic phase sensitive; and etoposide, gap 2 phase sensitive).

METHODS

Rats were respectively administered docetaxel (100 mg/kg) or etoposide (110 mg/kg) by intraperitoneal injection for 4 consecutive days. Then the rats were divided randomly into a LIPUS group and a non-LIPUS group. In the LIPUS group, the right femoral metaphysis of rats was treated by LIPUS (acoustic intensity, 200 mW/cm² ; frequency, 0.3 MHz; and duty cycle, 20%) for 20 minutes on 7 consecutive days from day 5. The rats of the non-LIPUS group were treated without ultrasound output. A blood cell count, an enzyme-linked immunosorbent assay, a real-time quantitative polymerase chain reaction, and hematoxylin-eosin staining were applied to detect the results.

RESULTS

Low-intensity pulsed ultrasound significantly promoted the counts of bone marrow nucleated cells, white blood cells, immunoglobulin A (IgA), IgG, granulocyte colony-stimulating factor, stem cell factor, and intercellular cell adhesion molecule 1 and reduced the counts of vascular cell adhesion molecule 1 whether in the docetaxel or etoposide group (P < .05). Low-intensity pulsed ultrasound only increased the expression level of IgM in the docetaxel group but decreased the level of interleukin 6 in the etoposide group (P < .05).

CONCLUSIONS

Low-intensity pulsed ultrasound has potential to be a noninvasive treatment for myelosuppression caused by different cell cycle-sensitive chemotherapy drugs.

Human umbilical cord mesenchymal stem cell transplantation restores hematopoiesis in acute radiation disease

OBJECTIVE

Nuclear technology has been widely used in military and civilian fields, and radiotherapy is an effective and common form of treatment for cancer. However, acute radiation disease caused by high doses of radiation is a serious complication. The aim of this study was to investigate the chance of mitigating radiation-triggered hematopoiesis failure using human umbilical cord mesenchymal stem cell (HUCMSC) transplantation.

METHODS

Umbilical cords were obtained from three full-term female neonatus through cesarean section at Xinqiao Hospital. Bone marrow mesenchymal stem cells (BMSCs) were cultivated as depicted before. Briefly, monocytes were collected from bone marrow blood by means of density separation columns. An acute radiation disease mouse model was established to compare the restoration effect of HUCMSCs and BMSCs transplanted via the tail vein. The hematopoietic stem cell transplantation (HSCT) mouse model was obtained through bone marrow cell transplantation (BMCT) from C57BL/6 mice (H-2b, donor) to female CB6F1 mice (H-2b×d, recipient) after irradiation. The mice were divided into five groups, including control (saline), irradiated (radiation), bone marrow (HSCT, transplanted 1×10⁶ BM cells), HUCMSC (transplanted a mixture of 1×10⁶ HUCMSCs and 1×10⁶ BM cells), and BMSC group (transplanted a mixture of 1×10⁶ BMSCs and 1×10⁶ BM cells). The blood condition results were used to test the radiation-induced inflammatory reaction, and bone marrow pathological staining (H&E) was used to determine the radiation-induced bone marrow hematopoiesis failure.

RESULTS

After radiation, HUCMSC transplantation significantly improved the survival rate. By analyzing the blood condition test, colony formation, and bone marrow pathology, it was found that the HUCMSC group demonstrated significant functional improvements in terms of the recovery from hematopoiesis failure and reduction of inflammatory reaction.

CONCLUSIONS

HUCMSCs have more advantages over BMSCs in restoring and promoting the recovery of radiation-induced hematopoietic damage, thus having a new therapeutic potential for patients with acute radiation disease.

Chemical and biological basis for development of novel radioprotective drugs for cancer therapy

Ionizing radiation (IR) causes chemical changes in biological systems through direct interaction with the macromolecules or by causing radiolysis of water. This property of IR is harnessed in the clinic for radiotherapy in almost 50% of cancers patients. Despite the advent of stereotactic radiotherapy instruments and other advancements in shielding techniques, the inadvertent deposition of radiation dose in the surrounding normal tissue can cause late effects of radiation injury in normal tissues. Radioprotectors, which are chemical or biological agents, can reduce or mitigate these toxic side-effects of radiotherapy in cancer patients and also during radiation accidents. The desired characteristics of an ideal radioprotector include low chemical toxicity, high risk to benefit ratio and specific protection of normal cells against the harmful effects of radiation without compromising the cytotoxic effects of IR on cancer cells. Since reactive oxygen species (ROS) are the major contributors of IR mediated toxicity, plethora of studies have highlighted the potential role of antioxidants to protect against IR induced damage. However, owing to the lack of any clinically approved radioprotector against whole body radiation, researchers have shifted the focus toward finding alternate targets that could be exploited for the development of novel agents. The present review provides a comprehensive insight in to the different strategies, encompassing prime molecular targets, which have been employed to develop radiation protectors/countermeasures. It is anticipated that understanding such factors will lead to the development of novel strategies for increasing the outcome of radiotherapy by minimizing normal tissue toxicity.

Effects and Predictive Factors of Immunosuppressive Therapy Combined with Umbilical Cord Blood Infusion in Patients with Severe Aplastic Anemia

PURPOSE

To investigate the efficacy and safety of umbilical cord blood (UCB) infusion (UCBI) plus immunosuppressive therapy (IST) treatment in comparison to IST treatment, as well as predictive factors for clinical responses, in severe aplastic anemia (SAA) patients.

MATERIALS AND METHODS

Totally, 93 patients with SAA were enrolled in this cohort study. In the IST group, rabbit antithymocyte globulin (r-ATG) combined with cyclosporine A (CsA) was administered, while in the IST+UBCI group, r-ATG, CsA, and UCB were used.

RESULTS

After 6 months of treatment, UCBI+IST achieved a higher complete response (CR) rate (p=0.002) and an elevated overall response rate (ORR) (p=0.004), compared to IST. Regarding hematopoietic recovery at month 6, platelet responses in the UCBI+IST group were better than those in the IST group (p=0.002), and UCBI+IST treatment facilitated increasing trends in absolute neutrophil count (ANC) response (p=0.056). Kaplan-Meier curves illuminated UCBI+IST achieved faster ANC response (p<0.001) and platelet response (p<0.001), compared with IST therapy. There was no difference in overall survival (OS) between the two groups (p=0.620). Furthermore, logistic regression analysis demonstrated that UCBI+IST was an independent predicting factor for both CR (p=0.001) and ORR (p<0.001), compared to IST; meanwhile, very severe aplastic anemia (VSAA) and ANC could predict clinical responses as well. However, Cox proportional hazard regression indicated that VSAA (p=0.003), but not UCBI+IST, affected OS. Safety profiles showed that UCBI+IST therapy did not elevate adverse events, compared with IST treatment.

CONCLUSION

UCBI+IST achieved better clinical responses and hematopoietic recovery than IST, and was well tolerated in SAA patients.

Human-derived normal mesenchymal stem/stromal cells in anticancer therapies

The tumor microenvironment (TME) not only plays a pivotal role during cancer progression and metastasis, but also has profound effects on therapeutic efficacy. Stromal cells of the TME are increasingly becoming a key consideration in the development of active anticancer therapeutics. However, dispute concerning the role of stromal cells to fight cancer continues because the use of mesenchymal stem/stromal cells (MSCs) as an anticancer agent is dependent on the specific MSCs subtype, in vitro or in vivo conditions, factors secreted by MSCs, types of cancer cell lines and interactions between MSCs, cancer cells and host immune cells. In this review, we mainly focus on the role of human-derived normal MSCs in anticancer therapies. We first discuss the use of different MSCs in the therapies for various cancers. We then focus on their anticancer mechanism and clinical application.

Increased expression of CX43 on stromal cells promotes leukemia apoptosis

Connexin 43 (Cx43) induced apoptosis has been reported in solid tumors, but the effect of Cx43 expressed by bone marrow stromal cells (BMSC) in leukemia has not been fully investigated. Manipulating Cx43 expression could be a potential therapeutic strategy for leukemia. Here, we investigate the effect of Cx43 expressed by BMSCs (human Umbilical Cord Stem Cells over-expressed CX43, Cx43-hUCSC) on leukemia cells. When co-cultured with Cx43-hUCSC, leukemia cells show significant lower growth rate with increasing apoptosis activity, and more leukemia cells enter S phase. Functional assays of fluorescence recovery after photo bleaching (FRAP) showed improved gap junctional intercellular communication (GJIC) on leukemia cells when co-cultured with Cx43-hUCSC (p < 0.01). In a mouse minimal disease model, the mean survival time and mortality rate were significantly improved in mice transplanted with Cx43-hUCSC. Our results indicate that Cx43 expressed by BMSC induces apoptosis on leukemia cells. Small molecules or other pharmaceutical approaches for modulating Cx43 expression in BMSCs could be used for delaying relapse of leukemia.

Mesenchymal stromal cell-derived extracellular vesicles rescue radiation damage to murine marrow hematopoietic cells

Mesenchymal stromal cells (MSCs) have been shown to reverse radiation damage to marrow stem cells. We have evaluated the capacity of MSC-derived extracellular vesicles (MSC-EVs) to mitigate radiation injury to marrow stem cells at 4 h to 7 days after irradiation. Significant restoration of marrow stem cell engraftment at 4, 24 and 168 h post irradiation by exposure to MSC-EVs was observed at 3 weeks to 9 months after transplant and further confirmed by secondary engraftment. Intravenous injection of MSC-EVs to 500cGy exposed mice led to partial recovery of peripheral blood counts and restoration of the engraftment of marrow. The murine hematopoietic cell line, FDC-P1 exposed to 500cGy, showed reversal of growth inhibition, DNA damage and apoptosis on exposure to murine or human MSC-EVs. Both murine and human MSC-EVs reverse radiation damage to murine marrow cells and stimulate normal murine marrow stem cell/progenitors to proliferate. A preparation with both exosomes and microvesicles was found to be superior to either microvesicles or exosomes alone. Biologic activity was seen in freshly isolated vesicles and in vesicles stored for up to 6 months in 10% dimethyl sulfoxide at -80 °C. These studies indicate that MSC-EVs can reverse radiation damage to bone marrow stem cells.

Human Wharton's jelly stem cells, its conditioned medium and cell-free lysate inhibit the growth of human lymphoma cells

Several groups have reported that primitive mesenchymal stem cells from the gelatinous matrix of the Wharton's jelly of the human umbilical cord (hWJSCs) possess tumoricidal properties and inhibit the growth of solid tumours such as human mammary carcinoma, ovarian carcinoma and osteosarcoma. This unique characteristic led to the hypothesis that hWJSCs serve as a natural defence against migrating cancer cells from mother to fetus thus explaining why tumorigenesis in the fetus is rare. However, it is not known whether non-solid malignant hematopoietic cells are also inhibited by hWJSCs and what the exact tumoricidal mechanisms are. We therefore evaluated the influence of hWJSCs and its extracts on Burkitt's lymphoma cells. Cell proliferation (BrdU and Ki67+), viability (MTT) and cell death (Annexin V-Propidium iodide and live/dead) assays showed significant inhibition of lymphoma cell growth after 48 h exposure to hWJSCs or its extracts compared to controls. Increased cell death was observed at sub-G1 and S and decreased proliferation at G2/M phases of the mitotic cycle. Superoxide dismutase and hydrogen peroxide activity were significantly increased and glutathione peroxidase significantly decreased in treated lymphoma cells. Time lapse imaging and confocal z-stack images showed yellow fluorescent in situ hybridization (FISH) signals of lymphoma cell Y chromosomes within the cytoplasm of female red labelled hWJSCs. We hypothesize that the growth of lymphoma cells is inhibited by the molecules secreted by hWJSCs that use oxidative stress pathways to induce cell death followed by engulfment of the apoptotic remains of the lymphoma cells by the hWJSCs.

Matrix metalloproteinases in stem cell mobilization

Hematopoietic stem cells (HSCs) have the capability to migrate back and forth between their preferred microenvironment in bone marrow niches and the peripheral blood, but under steady-state conditions only a marginal number of stem cells can be found in the circulation. Different mobilizing agents, however, which create a highly proteolytic milieu in the bone marrow, can drastically increase the number of circulating HSCs. Among other proteases secreted and membrane-bound matrix metalloproteinases (MMPs) are known to be involved in the induced mobilization process and can digest niche-specific extracellular matrix components and cytokines responsible for stem cell retention to the niches. Iatrogenic stem cell mobilization and stem cell homing to their niches are clinically employed on a routine basis, although the exact mechanisms of both processes are still not fully understood. In this review we provide an overview on the various roles of MMPs in the induced release of HSCs from the bone marrow.

Expression and inducibility of cytochrome P450s (CYP1A1, 2B6, 2E1, 3A4) in human cord blood CD34(+) stem cell-derived differentiating neuronal cells

The status of xenobiotic metabolism in developing human brain cells is not known. The reason is nonavailability of developing human fetal brain. We investigate the applicability of the plasticity potential of human umbilical cord blood stem cells for the purpose. Characterized hematopoietic stem cells are converted into neuronal subtypes in eight days. The expression and substrate-specific catalytic activity of the cytochrome P450s (CYPs) CYP1A1 and 3A4 increased gradually till day 8 of differentiation, whereas CYP2B6 and CYP2E1 showed highest expression and activity at day 4. There was no significant increase in the expression of CYP regulators, namely, aryl hydrocarbon receptor (AHR), constitutive androstane receptor (CAR), pregnane X receptor (PXR), and glutathione-S-transferase (GSTP1-1) during differentiation. Differentiating cells showed significant induction in the expression of CYP1A1, 2B6, 2E1, 3A4, AHR, CAR, PXR, and GSTP1-1 when exposed to rifampin, a known universal inducer of CYPs. The xenobiotic-metabolizing capabilities of these differentiating cells were confirmed by exposing them to the organophosphate pesticide monocrotophos (MCP), a known developmental neurotoxicant, in the presence and absence of a universal inhibitor of CYPs-cimetidine. Early-differentiating cells (day 2) were found to be more vulnerable to xenobiotics than mature well-differentiated cells. For the first time, we report significant expression and catalytic activity of selected CYPs in human cord blood hematopoietic stem cell-derived neuronal cells at various stages of maturity. We also confirm significant induction in the expression and catalytic activity of selected CYPs in human cord blood stem cell-derived differentiating neuronal cells exposed to known CYP inducers and MCP.