Unmodified Mesenchymal Stem Cells Research Articles

Abstract P3161: Engineering Mesenchymal Stem Cell-derived Extracellular Vesicles To Enhance Their Therapeutic Efficacy In Cardiovascular Disease

Background: Extracellular vesicles derived from cardiosphere-derived cells (CDC-EVs) have demonstrated the ability to regulate cardiomyocyte apoptosis and induce cardiomyocyte proliferation in pre-clinical models of acute MI. While CDC-EVs exhibit cardioprotective effects, they require invasive intramyocardial injections to achieve therapeutic efficacy, detracting from their translatability. Mesenchymal stem cells (MSC) also generate cardioprotective EVs (MSC-EVs), which have demonstrated therapeutic efficacy in models of cardiac disease following intravenous administration. However, MSC-EVs lack several of the cardioprotective miRs expressed by CDC-EVs, including miR146a, which has been shown to modulate cardiomyocyte apoptosis. The objective of our current study was to determine the effect of enriching MSC-EVs with cardioprotective CDC-EV miRNA on cardiomyocyte apoptosis. Methods: MSCs were transfected with miR-146a-5p mimics using Trans-IT TKO in serum free growth media. EVs were isolated using a combination of ultrafiltration and size exclusion chromatography (SEC) and characterized by size, morphology and expression of surface markers. RT-PCR was performed on EV samples to quantify miR-146a expression. Primary neonatal mouse cardiomyocytes were treated with MSC-EVs, miR-146a loaded MSC-EVs, CDC-EVs or matched volume vehicle control. Cardiomyocyte apoptosis was assessed by a TUNEL assay. Results: Treatment with miR-146a loaded MSC EVs reduced cardiomyocyte apoptosis compared with cardiomyocytes treated with unmodified MSC exosomes (14±1% vs. 31±3%) (mean ± SEM, p=0.001, one-way ANOVA). miR-146a loaded MSC-EVs and CDC-EVs demonstrated a similar level of reduction in cardiomyocyte apoptosis (14±1% vs. 15±1%). There was no difference in the level of apoptosis between cardiomyocytes treated with unmodified MSC exosomes and cardiomyocytes treated with vehicle control (31±3% vs. 27±1%) (mean ± SEM, p=0.366, one-way ANOVA). Conclusion: Engineering MSC-EVs to express miR-146a enhances their ability to reduce cardiomyocyte apoptosis in vitro . This highlights the potential of cargo engineering as a means to improve the therapeutic efficacy of EVs for cardiovascular disease.

Assessment of Risks and Benefits of Using Antibiotics Resistance Genes in Mesenchymal Stem Cell-Based Ex-Vivo Therapy.

Recently, ex-vivo gene therapy has emerged as a promising approach to enhance the therapeutic potential of mesenchymal stem cells (MSCs) by introducing functional genes in vitro. Here, we explored the need of using selection markers to increase the gene delivery efficiency and evaluated the potential risks associated with their use in the manufacturing process. We used MSCs/CD that carry the cytosine deaminase gene (CD) as a therapeutic gene and a puromycin resistance gene (PuroR) as a selection marker. We evaluated the correlation between the therapeutic efficacy and the purity of therapeutic MSCs/CD by examining their anti-cancer effect on co-cultured U87/GFP cells. To simulate in vivo horizontal transfer of the PuroR gene in vivo, we generated a puromycin-resistant E. coli (E. coli/PuroR) by introducing the PuroR gene and assessed its responsiveness to various antibiotics. We found that the anti-cancer effect of MSCs/CD was directly proportional to their purity, suggesting the crucial role of the PuroR gene in eliminating impure unmodified MSCs and enhancing the purity of MSCs/CD during the manufacturing process. Additionally, we found that clinically available antibiotics were effective in inhibiting the growth of hypothetical microorganism, E. coli/PuroR. In summary, our study highlights the potential benefits of using the PuroR gene as a selection marker to enhance the purity and efficacy of therapeutic cells in MSC-based gene therapy. Furthermore, our study suggests that the potential risk of horizontal transfer of antibiotics resistance genes in vivo can be effectively managed by clinically available antibiotics.

E-selectin Gene Modified Mesenchymal Stem Cell Therapy Reverses Impairments in Wound Healing in Ischemic Limbs

Tissue loss is a major source of morbidity and substantially worsens the risk of extremity amputation in patients with chronic limb-threatening ischemia (CLTI). Although cell-based therapies utilizing mesenchymal stem cells (MSC) hold significant promise to augment wound healing and therapeutic angiogenesis, unmodified MSCs have demonstrated only minor benefits for CLTI in previous clinical trials. Here we report the effects of MSCs engineered to overexpress E-selectin (E-sel), a cell adhesion molecule capable of inducing neovascularization, on a translational murine model recapitulating hindlimb ischemia with cutaneous tissue loss. MSCs were harvested from bone marrow of 8- to 10-week-old FVB/Rosa26SormTmG donor mice and cultured in MesenCult medium. MSCs were verified as CD44+/CD73+/CD105+/CD29+/Sca-1+ by flow cytometry. MSCs underwent viral transduction with E-sel-GFP/AAV or GFP/AAV. Femoral artery ligation was performed in 12- to 14-week-old recipient FVB mice followed by a 4-mm acute cutaneous wound in the ipsilateral limb and local injection of PBS or 1 × 106 donor GFP+/MSCs or E-sel+/MSCs (E-sel+/MSC). Wounds were monitored daily for 7 days, at which point tissue specimens were harvested for microscopy and whole-body DiI perfusion studies. Unmodified MSCs do not express basal levels of E-sel, and E-sel+/MSCs retained MSC phenotype and trilineage differentiation capability. Mice receiving E-sel+/MSC treatment (n = 10) demonstrated accelerated wound closure rates compared to both GFP+/MSCs (n = 10) and phosphate-buffered saline (PBS) (n = 10)-treated mice at each postoperative day (POD) with the highest degree of difference observed at POD 5 (94 ± 3% vs 79 ± 10% GFP vs 72 ± 9% PBS; P < .001) and 7 (98 ± 2% vs 86 ± 8% GFP vs 87 ± 6% PBS; P < .010). Collagen deposition was more abundant in wounds treated with E-sel+/MSCs (21 ± 4% vs 5 ± 1% GFP vs 9 ± 1% PBS). DiI perfusion at POD 10 demonstrated greater vessel density in wounds treated with E-sel+/MSCs (76 ± 15% vs 29 ± 7% GFP vs 9 ± 5% PBS relative vascular density). Wound healing focused polymerase chain reaction array identified upregulation of target genes in wound tissue responding to E-sel+/MSCs. E-sel+/MSCs demonstrated enhanced viability more mTmG+-E-sel+/MSCs (13 ± 3 cells/high powered field [HPF] vs GFP+/MSCs 3 ± 2 cells/HPF vs PBS 0 ± 0 cells/HPF; P < .010) observed at POD 7 on microscopy. Cell-based therapy using E-sel-overexpressing MSCs reverses impairments in wound healing of ischemic limbs. These data exhibit the potential role for E-sel-modified MSCs as a novel therapeutic alternative in future clinical applications for delayed and nonhealing wounds associated with CLTI.

Abstract 594: E-selectin-Overexpressing Mesenchymal Stem Cell-based Therapy Augments Cutaneous Wound Healing In Ischemic Limbs

Objective: Tissue loss considerably worsens the risk of extremity amputation in patients with chronic limb-threatening ischemia (CLTI), and unmodified mesenchymal stem cell (MSC) therapies have failed to demonstrate more than minor clinical benefits for inducing therapeutic angiogenesis and wound healing. Here we describe the effects of MSCs engineered to overexpress E-selectin, a cell-adhesion molecule capable of stimulating neovascularization, using a translational murine model recapitulating hindlimb ischemia with cutaneous tissue loss. Methods: MSCs were harvested from bone marrow of 8-10-week-old FVB/Rosa26Sor mTmG donor mice and verified as CD44 + /CD73+/CD105 + /CD29 + /Sca-1 + by flow cytometry. MSCs underwent viral transduction with E-selectin-GFP/AAV or GFP/AAV. Femoral artery ligation was performed in 12-14-week-old recipient FVB mice followed by a 4 mm cutaneous wound in the ipsilateral limb and local injection of PBS or 1x10^6 donor GFP + /MSCs or E-selectin + /MSCs (E-sel + /MSC). Wounds were monitored daily for 7 days and then harvested. Results: Unmodified MSCs do not express E-selectin, and E-sel + /MSCs retained MSC phenotype. Mice receiving E-sel + /MSC treatment (n=10) demonstrated accelerated wound closure compared to both GFP + /MSCs (n=10) and PBS (n=10) treated mice at each post-operative day (POD) with the highest degree of difference observed at POD 5 (94 ± 3% vs. 79 ± 10% GFP vs. 72 ± 9% PBS, p&lt;0.001) and 7 (98 ± 2% vs. 86 ± 8% GFP vs. 87 ± 6% PBS; p&lt;0.010). Collagen deposition was greater in wounds treated with E-sel + /MSCs (21 ± 4% vs. 5 ± 1% GFP vs. 9 ± 1% PBS). DiI perfusion at POD 10 demonstrated greater vessel density in wounds treated with E-sel + /MSCs (76 ± 15% vs. 29 ± 7% GFP vs. 9 ± 5% PBS relative vascular density). E-sel + /MSCs demonstrated improved viability with more mTmG + -E-sel + /MSCs (13 ± 3 cells/high powered field (HPF) vs. GFP + /MSCs 3 ± 2 cells/HPF vs. PBS 0 ± 0 cells/HPF, p&lt;0.010) at POD 7 on immunofluorescent microscopy. Conclusion: Cell therapy using E-selectin-overexpressing MSCs overcomes impairments in wound healing of ischemic limbs. These data exhibit the potential role for E-selectin-modified MSCs as a novel cell therapy in future clinical applications for delayed and non-healing wounds associated with CLTI.

Methods and Limitations of Augmenting Mesenchymal Stem Cells for Therapeutic Applications.

Significance: Given their capacity for self-renewal, multilineage differentiation, and immunomodulatory potential, mesenchymal stem cells (MSCs) represent a promising modality of clinical therapy for both regenerative medicine and immune diseases. In this study, we review the key approaches and popular methods utilized to boost potency and modify functions of MSCs for clinical purposes as well as their associated limitations. Recent Advances: Several major domains of cell modification strategies are currently employed by investigators to overcome these deficits and augment the therapeutic potential of MSCs. Priming MSCs with soluble factors or pharmacologic agents as well as manipulating oxygen availability in culture have been demonstrated to be effective biochemical methods to augment MSC potential. Distinct genetic and epigenetic methods have emerged in recent years to modify the genetic expression of target proteins and factors thereby modulating MSCs capacity for differentiation, migration, and proliferation. Physical methods utilizing three-dimensional culture methods and alternative cell delivery systems and scaffolds can be used to recapitulate the native MSC niche and augment their engraftment and viability for in vivo models. Critical Issues: Unmodified MSCs have demonstrated only modest benefits in many preclinical and clinical studies due to issues with cell engraftment, viability, heterogeneity, and immunocompatibility between donor and recipient. Furthermore, unmodified MSCs can have low inherent therapeutic potential for which intensive research over the past few decades has been dedicated to improving cell functionality and potency.

ZipperCells Exhibit Enhanced Accumulation and Retention at the Site of Myocardial Infarction.

There has been extensive interest in cellular therapies for the treatment of myocardial infarction, but bottlenecks concerning cellular accumulation and retention remain. Here, a novel system of in situ crosslinking mesenchymal stem cells (MSCs) for the formation of a living depot at the infarct site is reported. Bone marrow-derived mesenchymal stem cells that are surface decorated with heterodimerizing leucine zippers, termed ZipperCells, are engineered. When delivered intravenously in sequential doses, it is demonstrated that ZipperCells can migrate to the infarct site, crosslink, and show ≈500% enhanced accumulation and ≈600% improvement in prolonged retention at 10 days after injection compared to unmodified MSCs. This study introduces an advanced approach to creating noninvasive therapeutics depots using cellular crosslinking and provides the framework for future scaffold-free delivery methods for cardiac repair.

Application of mesenchymal stem cells in tumor therapy.

Mesenchymal stem cells (MSCs) are multipotent stem cells that exist widely in the human body, which can self-renewal and differentiate into different types of cell. Due to its advantages of tumor tissue tropism and easy to be engineered, it has been widely used in cancer treatment research recently. However, the tumor-promoting or anti-tumor effect of MSCs is controversial, especially for unmodified MSCs. Therefore, researchers are more inclined to use MSCs as carriers to engineer them. With the deepening in understanding of vesicles, it is found that the vesicles derived from MSCs seem to have greater advantages as carriers. Although the current research of MSCs in the treatment of tumors has been initiated in the clinic, there are still many problems to be solved in the pre-clinical application.

Abstract 378: Bioengineering enucleated cell vehicles for tumor targeted intravenous delivery of oncolytic viruses

Abstract Metastatic triple negative breast cancer (TNBC) includes poor prognoses and limited effective therapies. The prevalence of systemic micro-metastases is a major barrier to achieving durable clinical outcomes. Oncolytic viruses (OVs) have garnered attention as anti-cancer adjuvants due to their potential for systemic delivery and ability to lyse tumor cells while leaving healthy cells unaffected. Clinical trials have been conducted testing the efficacy of OVs on diverse cancers. Although targeting distributed metastases can be accomplished by intravenous (IV) administration, administration of virus into patient vasculature is inefficient due to the clearance of unprotected viruses by host immunity. There is a major unmet need to develop biocompatible carriers that improve delivery of OVs by circumventing host anti-viral immunity while homing to metastatic lesions. Mesenchymal stem cells (MSCs) are ideal OV carriers as they display innate tumor-trophic properties, propagate OVs, and shield virions from immunity until reaching their target. However, issues need to be addressed before MSCs can deliver OVs to patients: tumor homing needs improved and unmodified MSCs can engraft and contribute to tumor growth and metastasis, raising safety concerns. To address these limitations, our laboratory developed a MSC-derived biodelivery vehicle with enhanced homing abilities to deliver biologics, such as OVs, directly to tumors. Our approach involved using scRNA-seq to identify chemoattractant receptor/ligand pairs (CXCR4/CXCL12, CCR2/CCL2) and endothelial adhesion molecules (PSGL-1/P-E-Selectins) that mediate leukocyte tumor homing and extravasation. We then lentivirally expressed these receptors in MSCs and removed all DNA using ultracentrifugation and Ficoll density gradients. These bioengineered enucleated MSCs (Cargocytes™) have a defined lifespan (4 days) and robustly home to TNBC. This is an important breakthrough as TNBC-trophic Cargocytes can be scaled for clinical applications and are safe for in vivo use as described in our recent publication (Nature Biomedical Engineering, in press). OVs replicate in and lyse interferon-deficient tumor cells while having negligible effects on healthy cells. As the interferon response is absent in enucleated cells, Cargocytes support robust replication of OVs, including oncolytic Herpes Simplex Virus, Measles Virus, and Vesicular Stomatitis Virus (oVSV), allowing IV delivery of high titer OVs to tumors. In in vivo mouse models of metastatic TNBC, carrier-free oVSV fails to infect lung metastases. However, Cargocytes efficiently deliver oVSV to distributed micro-metastases and integrate deep into macro-metastases, evidencing a remarkable improvement in tissue distribution over intra-tumoral injections. Our findings suggest Cargocytes host and target oVSV directly to TNBC, constituting a highly specific OV delivery vehicle. Citation Format: Jeffrey White, Huawei Wang, Flavia Franco Da Cunha, Maureen Ruchhoeft, Richard Klemke. Bioengineering enucleated cell vehicles for tumor targeted intravenous delivery of oncolytic viruses [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 378.

Abstract 3519: Bioengineering enucleated cell vehicles for targeted delivery of Interleukin 12 to metastatic tumors

Abstract Metastatic triple negative breast cancer (TNBC) includes poor prognoses and limited effective therapies. Metastasis is the major barrier to durable clinical responses as many patients appear cured of their disease, yet return to clinic with recurrences from dormant micro-metastases. Immune activating agents, such as Interleukin 12 (IL-12) have attracted attention as anti-cancer adjuvants due to their ability to elicit systemic anti-cancer immunity. Although targeting distributed metastases can be accomplished by intravenous (IV) administration, administration of IL-12 into patient vasculature is highly inefficient due to its short half-life and poor toxicity profile. There is a major unmet need to develop biocompatible carriers that improve targeted delivery of IL-12 by specifically homing to metastatic lesions. Mesenchymal stem cells (MSCs) are considered ideal biodelivery vehicles as they display innate tumor-trophism and can deliver biomolecules specifically to systemic metastases. However, major issues need to be addressed before MSCs can be used to deliver IL-12 to patients: MSC tumor homing needs to be improved, and unmodified MSCs can engraft and contribute to tumor growth and metastasis, raising legitimate safety concerns. To address these major limitations, our laboratory developed a MSC-derived biodelivery vehicle with enhanced homing abilities to deliver biomolecules directly to tumors. Our approach involved using scRNA-seq to identify chemoattractant receptor/ligand pairs (CXCR4/CXCL12, CCR2/CCL2) and endothelial adhesion molecules (PSGL-1/P-E-Selectins) that mediate leukocyte homing and extravasation. We then lentivirally expressed these receptors in MSCs and removed nuclei using Ficoll gradient ultracentrifugation. These bioengineered enucleated MSCs (termed Cargocytes™) have a defined lifespan (4 days) and robustly home to TNBC. This is an important breakthrough as TNBC-trophic Cargocytes can be scaled for clinical applications and are safe for in vivo use as described in our recent publication (Nature Biomedical Engineering, in press). By using syngeneic mouse models of metastatic TNBC, we have observed IV-injected Cargocytes robustly extravasate and precisely home to metastatic lung nodules, suggesting Cargocytes act as remarkable biodelivery vehicles. Indeed, the tumor-trophism of Cargocytes includes both integrating into large macro-metastases and homing to broadly distributed micro-metastases. Cargocytes effectively produce and deliver high doses of IL-12 to mouse TNBC, which induces strong immune activation in tumors. This immune activation involved a potent anti-metastatic response, evidencing strong therapeutic efficacy. These findings suggest Cargocyte-delivered IL-12 could constitute a safe, potent, and highly specific anti-metastatic therapy for TNBC and other metastatic cancers sharing similar chemoattractant profiles. Citation Format: Jeffrey White, Huawei Wang, Flavia Franco Da Cunha, Maureen Ruchhoeft, Richard Klemke. Bioengineering enucleated cell vehicles for targeted delivery of Interleukin 12 to metastatic tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3519.

Galectin-9 Mediates the Therapeutic Effect of Mesenchymal Stem Cells on Experimental Endotoxemia.

Endotoxemia remains a major cause of mortality in the intensive care unit, but the therapeutic strategy is still lacking. Mesenchymal stem cell (MSC) was reported with a tissue-oriented differentiation ability and an excellent immunoregulatory capacity. However, the immunity signaling pathways that govern MSC modulation effect are not completely understood. In our current study, MSCs (2.5 × 105 /ml) were obtained and stimulated with IFN-γ (20 ng/ml) for 72 h. Gal-9 expression on MSCs was measured by ELISA, RT-PCR, flow cytometry, and immunofluorescence, respectively. Experimental endotoxemia was induced by LPS injection (10 mg/kg, i. p.) followed by the treatment with Gal-9 high-expressing MSCs, unmodified MSCs, and Gal-9 blocking MSCs. Therapeutic effects of MSCs were assessed by monitoring murine sepsis score, survival rate, splenocyte proportion rate, inflammatory mediator levels, and pathological manifestations. The results showed that Gal-9 expressed in MSCs, and this expression was increased in a dose-dependent manner after pre-stimulating with IFN-γ. Adoptive transfer of Gal-9 high-expressing MSCs into modeling mice significantly alleviated endotoxemia symptoms and multi-organ pathological damages. Splenocyte analysis indicated that Gal-9 high-expressing MSCs could promote macrophage polarization to M2-subtype and boost Treg generation. Moreover, there were also attenuated pro-inflammatory mediator expressions (TNF-α, IL-1β, IFN-γ, and iNOS), and increased anti-inflammatory mediator expressions (T-SOD and IL-35) in the sera and damaged organ homogenates. Additionally, we found a higher expression of Gal-9 in liver, lung, and kidney homogenate. Taken together, this study reveals that the optimized immunoregulatory effect of MSCs is strongly correlated with Gal-9 high expression, which provides a novel idea for the investigation of MSC immunomodulatory mechanisms and offers a potential strategy for the treatment of endotoxemia in clinical settings.

Engineered Small Extracellular Vesicles as a FGL1/PD-L1 Dual-Targeting Delivery System for Alleviating Immune Rejection.

There is an urgent need for developing new immunosuppressive agents due to the toxicity of long‐term use of broad immunosuppressive agents after organ transplantation. Comprehensive sample analysis revealed dysregulation of FGL1/LAG‐3 and PD‐L1/PD‐1 immune checkpoints in allogeneic heart transplantation mice and clinical kidney transplant patients. In order to enhance these two immunosuppressive signal axes, a bioengineering strategy is developed to simultaneously display FGL1/PD‐L1 (FP) on the surface of small extracellular vesicles (sEVs). Among various cell sources, FP sEVs derived from mesenchymal stem cells (MSCs) not only enriches FGL1/PD‐L1 expression but also maintain the immunomodulatory properties of unmodified MSC sEVs. Next, it is confirmed that FGL1 and PD‐L1 on sEVs are specifically bound to their receptors, LAG‐3 and PD‐1 on target cells. Importantly, FP sEVs significantly inhibite T cell activation and proliferation in vitro and a heart allograft model. Furthermore, FP sEVs encapsulated with low‐dose FK506 (FP sEVs@FK506) exert stronger effects on inhibiting T cell proliferation, reducing CD8+ T cell density and cytokine production in the spleens and heart grafts, inducing regulatory T cells in lymph nodes, and extending graft survival. Taken together, dual‐targeting sEVs have the potential to boost the immune inhibitory signalings in synergy and slow down transplant rejection.

Sex Differences in Mesenchymal Stem Cell Therapy With Gelatin-Based Microribbon Hydrogels in a Murine Long Bone Critical-Size Defect Model.

Mesenchymal stem cell (MSC)-based therapy and novel biomaterials are promising strategies for healing of long bone critical size defects. Interleukin-4 (IL-4) over-expressing MSCs within a gelatin microribbon (µRB) scaffold was previously shown to enhance the bridging of bone within a critical size femoral bone defect in male Balb/c mice. Whether sex differences affect the healing of this bone defect in conjunction with different treatments is unknown. In this study, we generated 2-mm critical-sized femoral diaphyseal bone defects in 10–12-week-old female and male Balb/c mice. Scaffolds without cells and with unmodified MSCs were implanted immediately after the primary surgery that created the bone defect; scaffolds with IL-4 over-expressing MSCs were implanted 3 days after the primary surgery, to avoid the adverse effects of IL-4 on the initial inflammatory phase of fracture healing. Mice were euthanized 6 weeks after the primary surgery and femurs were collected. MicroCT (µCT), histochemical and immunohistochemical analyses were subsequently performed of the defect site. µRB scaffolds with IL-4 over-expressing MSCs enhanced bone healing in both female and male mice. Male mice showed higher measures of bone bridging and increased alkaline phosphatase (ALP) positive areas, total macrophages and M2 macrophages compared with female mice after receiving scaffolds with IL-4 over-expressing MSCs. Female mice showed higher Tartrate-Resistant Acid Phosphatase (TRAP) positive osteoclast numbers compared with male mice. These results demonstrated that sex differences should be considered during the application of MSC-based studies of bone healing.

Mesenchymal stem cells as professional actors in gastrointestinal cancer therapy: From Naïve to genetically modified.

Considering the high incidence and mortality rate of gastrointestinal cancers (GIs) worldwide and partial success of the current available GI cancer treatments, there is a necessity to discover more effective approaches in cancer therapy. The failure in conventional therapies seems to be related to the resistance of cancer cells to chemotherapy, inability to target tumor cells especially in metastatic cancers, deficient drug concentrations in tumor sites, and unfavorable effects on pivotal non-malignant bodily tissues following systemic administration. In this context, we need an appropriate carrier for the delivery of therapeutic agents specifically to the GI cancer site. Mesenchymal stem cells (MSCs), a prominent cell-based strategy for cancer treatment, overcome various cancer therapy limitations and could be used as vehicles to deliver many anticancer agents such as therapeutic genes (DNA or interference RNA), oncolytic viruses, and chemotherapeutic or nanoparticle drugs. Moreover, secreted molecules of unmodified MSCs lead to deregulation of several proteins and different signaling pathways eradicating cancer cells. In the present review, at first, we overview the characteristics and utility of MSCs in cancer therapy, secondly, we discuss the application of naïve MSCs and utilization of MSCs in the delivery of therapeutic agents in GI cancer therapy and, finally, more information about harnessing of genetically modified MSCs in GI cancer treatment will be presented.

Mesenchymal stem cells overexpressing heme oxygenase-1 ameliorate lipopolysaccharide-induced acute lung injury in rats.

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are common and potentially lethal clinical syndromes characterized by acute respiratory failure resulting from excessive pulmonary inflammation, noncardiogenic pulmonary edema, and alveolar-capillary barrier disruption. At present, there is no effective and specific therapy for ALI/ARDS. Mesenchymal stem cells (MSCs) have well-known therapeutic potential in patients with ALI/ARDS. Heme oxygenase-1 (HO-1), a cytoprotective enzyme, possesses antioxidative, anti-inflammatory, and antiapoptotic effects. Thus, a combination of MSC transplantation with HO-1 delivery may have an additional protective effect against ALI/ARDS. This study investigated the effect of HO-1-modified bone-marrow-derived MSCs (MSCs-HO-1) on lipopolysaccharide (LPS)-induced ALI and its underlying mechanisms. We established MSCs-HO-1 through lentiviral transduction. The ALI rat model was established by successive LPS inhalations following injection with MSCs-HO-1. The survival rate, histological changes in the lungs, total protein concentration and neutrophil counts in bronchoalveolar lavage fluid, lung wet/dry weight ratio, cytokine levels in serum and lungs, nuclear transcription factor-κB activity, and protein expression of Toll-like receptor 4 signaling adaptors were examined. Furthermore, the cell viability, apoptosis, and paracrine activity of MSCs-HO-1 were examined under inflammatory stimuli in vitro. MSCs-HO-1 injection improved these parameters compared with primary unmodified MSCs. Moreover, MSCs-HO-1 had superior prosurvival and antiapoptotic properties and enhanced paracrine functions in vitro. Therefore, MSCs-HO-1 exert an enhanced protective effect to alleviate LPS-induced ALI in rats, and the mechanisms may be partially associated with superior prosurvival, antiapoptosis, and enhanced paracrine functions of MSCs-HO-1. These findings provide a novel insight into MSC-based therapeutic strategies for treating ALI/ARDS.

NFκB sensing IL-4 secreting mesenchymal stem cells mitigate the proinflammatory response of macrophages exposed to polyethylene wear particles.

Total joint replacement is a highly effective treatment for patients with end-stage arthritis. Proinflammatory macrophages (M1) mediate wear particle-associated inflammation and bone loss. Anti-inflammatory macrophages (M2) help resolve tissue damage and favor bone regeneration. Mesenchymal stem cell (MSC)-based therapy mitigates the M1 dominated inflammatory reaction and favorably modulates the bone remodeling process. In the current study, the immunomodulating ability of (1) unmodified MSCs, (2) MSCs preconditioned by NFκB stimulating ligands [lipopolysaccharide (LPS) plus TNFα], and (3) genetically modified MSCs that secrete IL-4 as a response to NFκB activation (NFκB-IL4) was compared in a macrophage/MSC co-culture system. Sterile or LPS-contaminated ultra-high molecular weight polyethylene particles were used to induce the proinflammatory responses in the macrophages. Contaminated particles induced M1 marker expression (TNFα, IL1β, and iNOS), while NFκB-IL4 MSCs modulated the macrophages from an M1 phenotype into a more favorable M2 phenotype (Arginase 1/Arg 1 and CD206 high). The IL4 secretion by NFκB-IL4 MSCs was significantly induced by the contaminated particles. The induction of Arg 1 and CD206 in macrophages via the preconditioned or naïve MSCs was negligible when compared with NFκB-IL4 MSC. Our findings indicated that NFκB-IL4 MSCs have the "on-demand" immunomodulatory ability to mitigate wear particle-associated inflammation with minimal adverse effects. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2744-2752, 2018.

Antimicrobial Peptide Combined with BMP2-Modified Mesenchymal Stem Cells Promotes Calvarial Repair in an Osteolytic Model.

Repair and regeneration of inflammation-induced bone loss remains a clinical challenge. LL37, an antimicrobial peptide, plays critical roles in cell migration, cytokine production, apoptosis, and angiogenesis. Migration of stem cells to the affected site and promotion of vascularization are essential for tissue engineering therapy, including bone regeneration. However, it is largely unknown whether LL37 affects mesenchymal stem cell (MSC) behavior and bone morphogenetic protein 2 (BMP2)-mediated bone repair during the bone pathologic remodeling process. By performing invitro and invivo studies with MSCs and a lipopolysaccharide (LPS)-induced mouse calvarial osteolytic bone defect model, we found that LL37 significantly promotes cell differentiation, migration, and proliferation in both unmodified MSCs and BMP2 gene-modified MSCs. Additionally, LL37 inhibited LPS-induced osteoclast formation and bacterial activity invitro. Furthermore, the combination of LL37 and BMP2 markedly promoted MSC-mediated angiogenesis and bone repair and regeneration in LPS-induced osteolytic defects in mouse calvaria. These findings demonstrate for the first time that LL37 can be a potential candidate drug for promoting osteogenesis and for inhibiting bacterial growth and osteoclastogenesis, and that the combination of BMP2 and LL37 is ideal for MSC-mediated bone regeneration, especially for inflammation-induced bone loss.

Periostin Upregulates Wnt/\u03b2-Catenin Signaling to Promote the Osteogenesis of CTLA4-Modified Human Bone Marrow-Mesenchymal Stem Cells

The enhanced osteogenesis of mesenchymal stem cells (MSCs) modified by expression of cytotoxic T lymphocyte-associated antigen 4 (CTLA4) has been shown in previous studies, but the mechanism remains unknown. Here we found that the bone repair effect of CTLA4-modified MSCs in demineralized bone matrix (DBM) in a rabbit radius defect model was significantly better than that observed for unmodified MSCs in DBM or DBM alone, and the periostin (POSTN) expression in CTLA4-modified MSCs was significantly higher than that in unmodified MSCs both in vivo and in vitro. In addition, we also found that treatment of CTLA4-modified MSCs with soluble POSTN could inhibit the glycogen synthase kinase-3β activity and increase β-catenin expression through up-regulation of lipoprotein-related protein-6 phosphorylation to promote osteogenic differentiation, but blocking of integrin αvβ3, a receptor of POSTN, could suppress these effects. Our data demonstrated that POSTN expressed in response to CTLA4 can promote the osteogenesis of xenotransplanted MSCs through interaction with Wnt/β-catenin pathway.

MiR-211/STAT5A Signaling Modulates Migration of Mesenchymal Stem Cells to Improve its Therapeutic Efficacy.

Our previous study showed that the therapeutic effects of mesenchymal stem cells (MSCs) transplantation were improved by enhancing migration. MicroRNA-211 (miR-211) can modulate the migratory properties of some cell types by mechanisms that are not fully understood. This study was designed to investigate a possible role for miR-211 in MSC migration, and whether genetic manipulation of miR-211 in MSCs could be used to enhance its beneficial effects of cell transplantation. Transwell assays confirmed that MSCs migration of was significantly impaired by miR-211 knockdown but enhanced by miR-211 overexpression. MiR-211 overexpressing MSCs also exhibited significantly increased cell engraftment in the peri-infarct areas of female rat hearts 2 days after intravenous transplantation of male MSCs as shown by GFP tracking and SYR gene quantification. This conferred a significant decrease in infarct size and improved cardiac performance. By using a loss or gain of gene function approach, we demonstrated that miR-211 targeted STAT5A to modulate MSCs migration, possibly by interacting with MAPK signaling. Furthermore, the beneficial effects of miR-211 overexpression in MSCs were abolished by simultaneous overexpression of STAT5A whereas the negative effects of miR-211 silencing on MSC migration were rescued by simultaneous downregulation of STAT5A. Finally, using ChIP-PCR and luciferase assays, we provide novel evidence that STAT3 can directly bind to promoter elements that activate miR-211 expression. STAT3/miR-211/STAT5A signaling plays a key role in MSCs migration. Intravenous infusion of genetically modified miR-211 overexpressing MSCs conveys enhanced protection from adverse post-MI remodeling compared with unmodified MSCs. Stem Cells 2016;34:1846-1858.

A Meta-Analysis of Mesenchymal Stem Cells in Animal Models of Parkinson's Disease.

Multiple studies have been performed to evaluate the effects of mesenchymal stem cells (MSCs) in animal models of Parkinson's disease (PD). We performed a meta-analysis to estimate the treatment effect of unmodified MSCs on behavioral outcomes in preclinical studies of PD. We performed a systematic literature search to identify studies that used behavioral testing to evaluate the treatment effect of unmodified MSCs in PD models. Meta-analysis was used to determine pooled effect size for rotational behavior and limb function, and meta-regression was performed to explore sources of heterogeneity. Twenty-five studies, including three delivery routes, a wide range of doses, and multiple PD models, were examined. Significant improvement was seen in the pooled standardized mean difference (SMD) for both rotational behavior [SMD: 1.24, 95% confidence interval (95% CI): 0.84, 1.64] and limb function (SMD: 0.84, 95% CI: 0.01, 1.66). Using meta-regression, intravenous administration and higher dose had a larger effect on limb function. Treatment with MSCs improves behavioral outcomes in PD models. Our analyses suggest that MSCs could be considered for early-stage clinical trials in the treatment of PD.

Graphene oxide flakes as a cellular adhesive: prevention of reactive oxygen species mediated death of implanted cells for cardiac repair.

Mesenchymal stem cell (MSC) implantation has emerged as a potential therapy for myocardial infarction (MI). However, the poor survival of MSCs implanted to treat MI has significantly limited the therapeutic efficacy of this approach. This poor survival is primarily due to reactive oxygen species (ROS) generated in the ischemic myocardium after the restoration of blood flow. ROS primarily causes the death of implanted MSCs by inhibiting the adhesion of the MSCs to extracellular matrices at the lesion site (i.e., anoikis). In this study, we proposed the use of graphene oxide (GO) flakes to protect the implanted MSCs from ROS-mediated death and thereby improve the therapeutic efficacy of the MSCs. GO can adsorb extracellular matrix (ECM) proteins. The survival of MSCs, which had adhered to ECM protein-adsorbed GO flakes and were subsequently exposed to ROS in vitro or implanted into the ischemia-damaged and reperfused myocardium, significantly exceeded that of unmodified MSCs. Furthermore, the MSC engraftment improved by the adhesion of MSCs to GO flakes prior to implantation enhanced the paracrine secretion from the MSCs following MSC implantation, which in turn promoted cardiac tissue repair and cardiac function restoration. This study demonstrates that GO can effectively improve the engraftment and therapeutic efficacy of MSCs used to repair the injury of ROS-abundant ischemia and reperfusion by protecting implanted cells from anoikis.