Cardioprotection by placenta-derived stromal cells in a murine myocardial infarction model

Discovery of a multipotent cell type from the term human placenta

We report a unique population of multipotent cells isolated from the term human placenta, for the first time, that can differentiate into cardiomyocytes and vascular cells with clonal proliferative ability, migratory ability, and trancriptomic evidence of immune privilege. Caudal-type homeobox-2 (CDX2) is a conserved factor that regulates trophectoderm formation and placentation during early embryonic development but has not previously been implicated in developmentally conserved regenerative mechanisms. We had earlier reported that Cdx2 lineage cells in the mouse placenta are capable of restoring cardiac function after intravenous delivery in male mice with experimental cardiac injury (myocardial infarction). Here we demonstrate that CDX2-expressing cells are prevalent in the human chorion and are poised for cardiovascular differentiation. We examined the term placentas from 106 healthy patients and showed that isolated CDX2 cells can spontaneously differentiate into cardiomyocytes, functional vascular cells, and retain homing ability in vitro. Functional annotation from transcriptomics analysis supports enhanced cardiogenesis, vasculogenesis, immune modulation, and chemotaxis gene signatures in CDX2 cells. CDX2 cells can be clonally propagated in culture with retention of cardiovascular differentiation. Our data supports further use of this accessible and ethically feasible cell source in the design of therapeutic strategies for cardiovascular disease.

Emerging roles of mesenchymal stem cell therapy in patients with critical limb ischemia

Critical limb ischemia (CLI), the terminal stage of peripheral arterial disease (PAD), is characterized by an extremely high risk of amputation and vascular issues, resulting in severe morbidity and mortality. In patients with severe limb ischemia with no alternative therapy options, such as endovascular angioplasty or bypass surgery, therapeutic angiogenesis utilizing cell-based therapies is vital for increasing blood flow to ischemic regions. Mesenchymal stem cells (MSCs) are currently considered one of the most encouraging cells as a regenerative alternative for the surgical treatment of CLI, including restoring tissue function and repairing ischemic tissue via immunomodulation and angiogenesis. The regenerative treatments for limb ischemia based on MSC therapy are still considered experimental. Despite recent advances in preclinical and clinical research studies, it is not recommended for regular clinical use. In this study, we review the immunomodulatory features of MSC besides the current understanding of different sources of MSC in the angiogenic treatment of CLI subjects and their potential applications as therapeutic agents. Specifically, this paper concentrates on the most current clinical application issues, and several recommendations are provided to improve the efficacy of cell therapy for CLI patients.

Placenta-Derived Mesenchymal-like Adherent Stromal Cells as an Effective Cell Therapy for Cocaine Addiction in a Rat Model

Recent research points to mesenchymal stem cells’ potential for treating neurological disorders, especially drug addiction. We examined the longitudinal effect of placenta-derived mesenchymal stromal-like cells (PLX-PAD) in a rat model for cocaine addiction. Sprague–Dawley male rats were trained to self-administer cocaine or saline daily until stable maintenance. Before the extinction phase, PLX-PAD cells were administered by intracerebroventricular or intranasal routes. Neurogenesis was evaluated, as was behavioral monitoring for craving. We labeled the PLX-PAD cells with gold nanoparticles and followed their longitudinal migration in the brain parallel to their infiltration of essential peripheral organs both by micro-CT and by inductively coupled plasma-optical emission spectrometry. Cell locations in the brain were confirmed by immunohistochemistry. We found that PLX-PAD cells attenuated cocaine-seeking behavior through their capacity to migrate to specific mesolimbic regions, homed on the parenchyma in the dentate gyrus of the hippocampus, and restored neurogenesis. We believe that intranasal cell therapy is a safe and effective approach to treating addiction and may offer a novel and efficient approach to rehabilitation.

Mesenchymal Stem/Stromal Cells and Their Role in Oxidative Stress Associated with Preeclampsia

Preeclampsia (PE) is a serious medically important disorder of human pregnancy, which features de novo pregnancy-induced hypertension and proteinuria. The severe form of PE can progress to eclampsia, a convulsive, life-threatening condition. When placental growth and perfusion are abnormal, the placenta experiences oxidative stress and subsequently secretes abnormal amounts of certain pro-angiogenic factors (eg, PlGF) as well as anti-angiogenic factors (eg, sFlt-1) that enter the maternal circulation. The net effect is damage to the maternal vascular endothelium, which subsequently manifests as the clinical features of PE. Other than delivery of the fetus and placenta, curative treatments for PE have not yet been forthcoming, which reflects the complexity of the clinical syndrome. A major source of reactive oxygen species that contributes to the widespread maternal vascular endothelium damage is the PE-affected decidua. The role of decidua-derived mesenchymal stem/stromal cells (MSC) in normotensive and pathological placenta development is poorly understood. The ability to respond to an environment of oxidative damage is a "universal property" of MSC but the biological mechanisms that MSC employ in response to oxidative stress are compromised in PE. In this review, we discuss how MSC respond to oxidative stress in normotensive and pathological conditions. We also consider the possibility of manipulating the oxidative stress response of abnormal MSC as a therapeutic strategy to treat preeclampsia.

Human Placental Allograft Membranes: Promising Role in Cardiac Surgery and Repair

Despite the immense investment in research devoted to cardiovascular diseases, mechanisms of progression and potential treatments, it remains one of the leading causes of death in the world. Cellular based strategies have been explored for decades, having mixed results, while more recently inflammation and its role in healing, regeneration and disease progression has taken center stage. Placental membranes are immune privileged tissues whose native function is acting as a protective barrier during fetal development, a state which fosters regeneration and healing. Their unique properties stem from a complex composition of extracellular matrix, growth factors and cytokines involved in cellular growth, survival, and inflammation modulation. Placental allograft membranes have been used successfully in complex wound applications but their potential in cardiac wounds has only begun to be explored. Although limited, pre-clinical studies demonstrated benefits when using placental membranes compared to other standard of care options for pericardial repair or infarct wound covering, facilitating cardiomyogenesis of stem cell populations in vitro and supporting functional performance in vivo. Early clinical evidence also suggested use of placental allograft membranes as a cardiac wound covering with the potential to mitigate the predominantly inflammatory environment such as pericarditis and prevention of new onset post-operative atrial fibrillation. Together, these studies demonstrate the promising translational potential of placental allograft membranes as post-surgical cardiac wound coverings. However, the small number of publications on this topic highlights the need for further studies to better understand how to support the safe and efficient use of placenta allograft membranes in cardiac surgery.

Intramuscular and intratendinous placenta-derived mesenchymal stromal-like cell treatment of a chronic quadriceps tendon rupture

BACKGROUND

Quadriceps tendon ruptures (QTRs) are rare but debilitating injuries, often associated with chronic metabolic conditions or long-term steroid treatment. While the surgical treatment for acute QTRs is described thoroughly, no common strategy exists for the often frustrating treatment of chronic, reoccurring QTRs. The pro-angiogenic and immunomodulatory properties of placenta-derived adherent mesenchymal stromal-like (PLX-PAD) cells have been described to protect musculoskeletal tissues from inflammation and catabolic cytokine migration, yet little is known about the regenerative potential of PLX-PAD cells in repetitively damaged tendon tissue.

CASE

We report the case of an 80-year-old male patient with a chronic three-time QTR of his right knee. The quadriceps tendon was reconstructed applying a conventional suture anchor repair procedure combined with a synthetic mesh augmentation and additional intramuscular and intratendineous PLX-PAD cell injections as an individualized treatment approach. No adverse events were reported, and excellent radiological and functional outcomes with a passive range of motion of 0/0/120° knee extension-flexion were observed at the 12 month follow-up. Gait analysis confirmed restoration of joint motion, including gait speed, deficit in step length, and knee extensor muscle strength (pre-surgery: 0.98 m/s, 40 cm, 42.4 ± 12.4 N; 9 months post-surgery: 1.07 m/s, 0 cm, 10.4 ± 18.9 N) as well as hyperextension throughout stance and late swing phases (pre-surgery: -11.2 ± 0.9°; 9 months post-surgery: -2.7 ± 1.6°). Postoperative lymphocyte and cytokine analyses from the patient's peripheral blood serum suggested a systemic short-term immunoregulatory reaction with postoperatively increased interleukin (IL)-6 (pre-surgery: 0.79 pg/mL; day 1: 139.97 pg/mL; day 5: 5.58 pg/mL; 9 months: 1.76 pg/mL) and IL-10 (pre-surgery: 0.9 pg/mL; day 1: 1.21 pg/ mL; day 5: 0.3 pg/mL; 9 months: 0.34 pg/mL) levels that decreased again over time.

CONCLUSIONS

Herein, we demonstrate a successfully treated chronic QTR with a synergistic surgical and biological reconstructive treatment approach. This local add-on treatment with PLX-PAD cells may be considered in specific cases of chronic QTRs, not susceptible to traditional suture anchor procedures and which exhibit a high risk of treatment failure. Further scientific engagement is warranted to explore underlying immunomodulatory mechanisms of action behind PLX-PAD cell treatment for tendon injuries.

Placenta-Expanded Stromal Cell Therapy in a Rodent Model of Simulated Weightlessness

Long duration spaceflight poses potential health risks to astronauts during flight and re-adaptation after return to Earth. There is an emerging need for NASA to provide successful and reliable therapeutics for long duration missions when capability for medical intervention will be limited. Clinically relevant, human placenta-derived therapeutic stromal cells (PLX-PAD) are a promising therapeutic alternative. We found that treatment of adult female mice with PLX-PAD near the onset of simulated weightlessness by hindlimb unloading (HU, 30 d) was well-tolerated and partially mitigated decrements caused by HU. Specifically, PLX-PAD treatment rescued HU-induced thymic atrophy, and mitigated HU-induced changes in percentages of circulating neutrophils, but did not rescue changes in the percentages of lymphocytes, monocytes, natural killer (NK) cells, T-cells and splenic atrophy. Further, PLX-PAD partially mitigated HU effects on the expression of select cytokines in the hippocampus. In contrast, PLX-PAD failed to protect bone and muscle from HU-induced effects, suggesting that the mechanisms which regulate the structure of these mechanosensitive tissues in response to disuse are discrete from those that regulate the immune- and central nervous system (CNS). These findings support the therapeutic potential of placenta-derived stromal cells for select physiological deficits during simulated spaceflight. Multiple countermeasures are likely needed for comprehensive protection from the deleterious effects of prolonged spaceflight.

Expression of CD146 and Regenerative Cytokines by Human Placenta-Derived Mesenchymal Stromal Cells upon Expansion in Different GMP-Compliant Media

Mesenchymal stromal cells (MSCs) have been successfully employed in clinical applications. In most studies, autologous MSCs from the bone marrow (bmMSCs) were used, and others employed autologous adipose tissue-derived stromal cells (ADSCs). Recently, clinical feasibility studies provided evidence that MSCs from human term placenta (pMSCs) can be used for homologous therapy facilitating access to regenerative cells in emergency situations, when autologous cells are not available or not suitable. We therefore investigated the expression of MSC stemness marker CD146 and the expression of neuro- and myoregenerative cytokines by human pMSCs after expansion in three different media compliant with good manufacturing protocols (GMP) in comparison to pMSCs expanded in a commercial MSC expansion media. To replace xenobiotic serum in the GMP-compliant media employed in this study, either human serum, human serum plus platelet lysate (PLL), or human plasma plus PLL was used. We report that enrichment of media with PLL accelerates pMSC proliferation but reduces the expression of the stemness marker CD146 significantly, while PLL deprivation enhanced the CD146 expression. In contrast, the reduced expression of CD146 by PLL deprivation was not observed on bmMSCs. The expression of the cytokines investigated was not modulated significantly by PLL. We conclude that accelerated expansion of pMSCs in GMP-compliant media enriched by PLL reduces the expression of stemness marker CD146, but does not influence the expression of neuro- and myoregenerative cytokines.

Human mesenchymal stem cell treatment of premature ovarian failure: new challenges and opportunities

Premature ovarian failure (POF) is one of the common disorders found in women leading to 1% female infertility. Clinical features of POF are hypoestrogenism or estrogen deficiency, increased gonadotropin level, and, most importantly, amenorrhea. With the development of regenerative medicine, human mesenchymal stem cell (hMSC) therapy brings new prospects for POF. This study aimed to describe the types of MSCs currently available for POF therapy, their biological characteristics, and their mechanism of action. It reviewed the latest findings on POF to provide the theoretical basis for further investigation and clinical therapy.

Perinatal Cells: A Promising COVID-19 Therapy?

The COVID-19 pandemic has become a priority in the health systems of all nations worldwide. In fact, there are currently no specific drugs or preventive treatments such as vaccines. The numerous therapies available today aim to counteract the symptoms caused by the viral infection that in some subjects can evolve causing acute respiratory distress syndromes (ARDS) with consequent admission to intensive care unit. The exacerbated response of the immune system, through cytokine storm, causes extensive damage to the lung tissue, with the formation of edema, fibrotic tissues and susceptibility to opportunistic infections. The inflammatory picture is also aggravated by disseminated intravascular coagulation which worsens the damage not only to the respiratory system, but also to other organs. In this context, perinatal cells represent a valid strategy thanks to their strong immunomodulatory potential, their safety profile, the ability to reduce fibrosis and stimulate reparative processes. Furthermore, perinatal cells exert antibacterial and antiviral actions. This review therefore provides an overview of the characteristics of perinatal cells with a particular focus on the beneficial effects that they could have in patients with COVID-19, and more specifically for their potential use in the treatment of ARDS and sepsis.

Placenta-Derived Cell Therapy to Treat Patients With Respiratory Failure Due to Coronavirus Disease 2019

Supplemental Digital Content is available in the text.

Objectives:

To determine whether placental cell therapy PLacental eXpanded (PLX)-PAD (Pluristem Therapeutics, Haifa, Israel) may be beneficial to treating critically ill patients suffering from acute respiratory distress syndrome due to coronavirus disease 2019.

Design:

Retrospective case report of critically ill coronavirus disease 2019 patients treated with PLacental eXpanded (PLX)-PAD from March 26, 2020, to April 4, 2020, with follow-up through May 2, 2020.

Setting:

Four hospitals in Israel (Rambam Health Care Campus, Bnai Zion Medical Center, and Samson Assuta Ashdod University Hospital), and Holy Name Medical Center in New Jersey.

Patients:

Eight critically ill patients on invasive mechanical ventilation, suffering from acute respiratory distress syndrome due to coronavirus disease 2019.

Interventions:

Intramuscular injection of PLacental eXpanded (PLX)-PAD (300 × 10⁶ cells) given as one to two treatments.

Measurements and Main Results:

Mortality, time to discharge, and changes in blood and respiratory variables were monitored during hospitalization to day 17 posttreatment. Of the eight patients treated (median age 55 yr, seven males and one female), five were discharged, two remained hospitalized, and one died. By day 3 postinjection, mean C-reactive protein fell 45% (240.3–131.3 mg/L; p = 0.0019) and fell to 77% by day 5 (56.0 mg/L; p < 0.0001). Pao₂/Fio₂ improved in 5:8 patients after 24-hour posttreatment, with similar effects 48-hour posttreatment. A decrease in positive end-expiratory pressure and increase in pH were statistically significant between days 0 and 14 (p = 0.0032 and p = 0.00072, respectively). A decrease in hemoglobin was statistically significant for days 0–5 and 0–14 (p = 0.015 and p = 0.0028, respectively), whereas for creatinine, it was statistically significant between days 0 and 14 (p = 0.032).

Conclusions:

Improvement in several variables such as C-reactive protein, positive end-expiratory pressure, and Pao₂/Fio₂ was observed following PLacental eXpanded (PLX)-PAD treatment, suggesting possible therapeutic effect. However, interpretation of the data is limited due to the small sample size, use of concomitant investigational therapies, and the uncontrolled study design. The efficacy of PLacental eXpanded (PLX)-PAD in coronavirus disease 2019 should be further evaluated in a controlled clinical trial.

Management of Myocarditis-Related Cardiomyopathy in Adults

Myocarditis is generally a mild and self-limited consequence of systemic infection of cardiotropic viruses. However, patients can develop a temporary or permanent impairment of cardiac function including acute cardiomyopathy with hemodynamic compromise or severe arrhythmias. In this setting, specific causes of inflammation are associated with variable risks of death and transplantation. Recent translational studies suggest that treatments tailored to specific causes of myocarditis may impact clinical outcomes when added to guideline-directed medical care. This review summarizes recent advances in translational research that influence the utility of endomyocardial biopsy for the management of inflammatory cardiomyopathies. Emerging therapies for myocarditis based on these mechanistic hypotheses are entering clinical trials and may add to the benefits of established heart failure treatment.

Use of Human Placenta-Derived Cells in a Preclinical Model of Tendon Injury

BACKGROUND

Emerging data suggest that human cells derived from extraembryonic tissues may have favorable musculoskeletal repair properties. The purpose of this study was to determine whether the injection of human placenta-derived mesenchymal-like stromal cells, termed placental expanded cells (PLX-PAD), would improve tendon healing in a preclinical model of tendinopathy.

METHODS

Sixty male Sprague-Dawley rats underwent bilateral patellar tendon injection with either saline solution (control) or PLX-PAD cells (2 × 10 cells/100 µL) 6 days after collagenase injection to induce tendon degeneration. Animals were killed at specific time points for biomechanical, histological, and gene expression analyses of the healing patellar tendons.

RESULTS

Biomechanical testing 2 weeks after the collagenase injury demonstrated better biomechanical properties in the tendons treated with PLX-PAD cells. The load to failure of the PLX-PAD-treated tendons was higher than that of the saline-solution-treated controls at 2 weeks (77.01 ± 10.51 versus 58.87 ± 11.97 N, p = 0.01). There was no significant difference between the 2 groups at 4 weeks. There were no differences in stiffness at either time point. Semiquantitative histological analysis demonstrated no significant differences in collagen organization or cellularity between the PLX-PAD and saline-solution-treated tendons. Gene expression analysis demonstrated higher levels of interleukin-1β (IL-1β) and IL-6 early in the healing process in the PLX-PAD-treated tendons.

CONCLUSIONS

Human placenta-derived cell therapy induced an early inflammatory response and a transient beneficial effect on tendon failure load in a model of collagenase-induced tendon degeneration.

CLINICAL RELEVANCE

Human extraembryonic tissues, such as the placenta, are an emerging source of cells for musculoskeletal repair and may hold promise as a point-of-care cell therapy for tendon injuries.

PLX-PAD Cell Treatment of Critical Limb Ischaemia: Rationale and Design of the PACE Trial

BACKGROUND

Critical limb ischaemia (CLI) is a life threatening condition with a considerable risk of major amputation and death. Besides revascularisation, no treatment has been proven to reduce the risks. Therapeutic angiogenesis by gene or cell therapy has not demonstrated definitive evidence in randomised controlled trials. PLX-PAD is an "off the shelf" allogeneic placental derived, mesenchymal like cell therapy, which, in preclinical studies, has shown pro-angiogenic, anti-inflammatory, and regenerative properties. Favourable one year amputation free survival (AFS), and trends in reduction of pain scores and increase of tissue perfusion have been shown in two small, open label, phase I trials.

METHODS

The PACE study is a phase III randomised, double blind, multicentre, multinational placebo controlled, parallel group study to evaluate the efficacy, tolerability, and safety of intramuscular injections of PLX-PAD cells to treat patients with atherosclerotic CLI with minor tissue loss (Rutherford Category 5) up to the ankle level, who are unsuitable for revascularisation or carry an unfavourable risk benefit for that treatment. The study will enroll 246 patients, who after screening are randomised in a ratio of 2:1 to treatment with intramuscular injections of PLX-PAD 300 × 10⁶ cells or placebo on two occasions, eight weeks apart. The primary efficacy endpoint is time to major amputation or death (amputation free survival), which will be assessed in follow up of at least 12 months and up to 36 months.

CONCLUSIONS

Based on favourable pre-clinical and initial clinical study results, the PACE phase III randomised controlled trial will evaluate placenta derived PLX-PAD cell treatment in patients with critical limb ischaemia, with an unfavourable risk benefit for revascularisation. Clinicaltrials.gov: NCT03006770.

Rescue from lethal acute radiation syndrome (ARS) with severe weight loss by secretome of intramuscularly injected human placental stromal cells

BACKGROUND

Most current cell-based regenerative therapies are based on the indirect induction of the affected tissues repair. Xenogeneic cell-based treatment with expanded human placenta stromal cells, predominantly from fetal origin (PLX-RAD cells), were shown to mitigate significantly acute radiation syndrome (ARS) following high dose irradiation in mice, with expedited regain of weight loss and haematopoietic function. The current mechanistic study explores the indirect effect of the secretome of PLX-RAD cells in the rescue of the irradiated mice.

METHODS

The mitigation of the ARS was investigated following two intramuscularly (IM) injected 2 × 10⁶ PLX-RAD cells, 1 and 5 days following 7.7 Gy irradiation. The mice survival rate and their blood or bone marrow (BM) cell counts were followed up and correlated with multiplex immunoassay of a panel of related human proteins of PLX-RAD derived secretome, as well as endogenous secretion of related mouse proteins. PLX-RAD secretome was also tested in vitro for its effect on the induction of the migration of BM progenitors.

RESULTS

A 7.7 Gy whole body mice irradiation resulted in ~25% survival by 21 days. Treatment with two IM injections of 2 × 10⁶ PLX-RAD cells on days 1 and 5 after irradiation mitigated highly significantly the subsequent lethal ARS, with survival rate increase to nearly 100% and fast regain of the initial weight loss (P < 0,0001). This was associated with a significant faster haematopoiesis recovery from day 9 onwards (P < 0.01). Nine out of the 65 human proteins tested were highly significantly elevated in the mouse circulation, peaking on days 6-9 after irradiation, relative to negligible levels in non-irradiated PLX-RAD injected mice (P < 0.01). The highly elevated proteins included human G-CSF, GRO, MCP-1, IL-6 and lL-8, reaching >500 pg/mL, while MCP-3, ENA, Eotaxin and fractalkine levels ranged between ~60-160pg/mL. The detected radiation-induced PLX-RAD secretome correlated well with the timing of the fast haematopoiesis regeneration. The radiation-induced PLX-RAD secretome seemed to reinforce the delayed high levels secretion of related mouse endogenous cytokines, including GCSF, KC, MCP-1 and IL-6. Additional supportive in vitro studies also confirmed the ability of cultured PLX-RAD secretome to induce accelerated migration of BM progenitors.

CONCLUSIONS

A well-regulated and orchestrated secretion of major pro-regenerative BM supporting secretome in high dose irradiated mice, treated with xenogeneic IM injected PLX-RAD cells, can explain the observed mitigation of ARS. This seemed to coincide with faster haematopoiesis regeneration, regain of severe weight loss and the increased survival rate. The ARS-related stress signals activating the IM injected PLX-RAD cells for the remote secretion of the relevant human proteins deserve further investigation.

Immunomodulatory placental-expanded, mesenchymal stromal cells improve muscle function following hip arthroplasty

BACKGROUND

No regenerative approach has thus far been shown to be effective in skeletal muscle injuries, despite their high frequency and associated functional deficits. We sought to address surgical trauma-related muscle injuries using local intraoperative application of allogeneic placenta-derived, mesenchymal-like adherent cells (PLX-PAD), using hip arthroplasty as a standardized injury model, because of the high regenerative and immunomodulatory potency of this cell type.

METHODS

Our pilot phase I/IIa study was prospective, randomized, double blind, and placebo-controlled. Twenty patients undergoing hip arthroplasty via a direct lateral approach received an injection of 3.0 × 10⁸ (300 M, n = 6) or 1.5 × 10⁸ (150 M, n = 7) PLX-PAD or a placebo (n = 7) into the injured gluteus medius muscles.

RESULTS

We did not observe any relevant PLX-PAD-related adverse events at the 2-year follow-up. Improved gluteus medius strength was noted as early as Week 6 in the treatment-groups. Surprisingly, until Week 26, the low-dose group outperformed the high-dose group and reached significantly improved strength compared with placebo [150 M vs. placebo: P = 0.007 (baseline adjusted; 95% confidence interval 7.6, 43.9); preoperative baseline values mean ± SE: placebo: 24.4 ± 6.7 Nm, 150 M: 27.3 ± 5.6 Nm], mirrored by an increase in muscle volume [150 M vs. placebo: P = 0.004 (baseline adjusted; 95% confidence interval 6.0, 30.0); preoperative baseline values GM volume: placebo: 211.9 ± 15.3 cm³ , 150 M: 237.4 ± 27.2 cm³ ]. Histology indicated accelerated healing after cell therapy. Biomarker studies revealed that low-dose treatment reduced the surgery-related immunological stress reaction more than high-dose treatment (exemplarily: CD16+ NK cells: Day 1 P = 0.06 vs. placebo, P = 0.07 vs. 150 M; CD4+ T-cells: Day 1 P = 0.04 vs. placebo, P = 0.08 vs. 150 M). Signs of late-onset immune reactivity after high-dose treatment corresponded to reduced functional improvement.

CONCLUSIONS

Allogeneic PLX-PAD therapy improved strength and volume of injured skeletal muscle with a reasonable safety profile. Outcomes could be positively correlated with the modulation of early postoperative stress-related immunological reactions.

Advances in perinatal stem cells research: a precious cell source for clinical applications

Perinatal tissues possess numerous types of stem (stromal) cells, which are considered effective candidates for cell therapy. These tissues possess common characteristics of both embryonic and adult stem cells, and cell therapists have begun to use perinatal stem cells to treat several diseases. Despite their benefits, these cells are considered biological waste and usually discarded after delivery. This review highlights the characteristics and potential clinical applications in regenerative medicine of perinatal stem cell sources - cord blood hematopoietic stem cells, umbilical cord mesenchymal stem cells, amniotic membrane stem cells, amniotic fluid stem cells, amniotic epithelial cells and chorionic mesenchymal stem cells.

Incorporating placental tissue in cord blood banking for stem cell transplantation

INTRODUCTION

Human term placenta is comprised of various tissues from which different cells can be obtained, including hematopoietic stem cells and mesenchymal stem/stromal cells (MSCs). Areas covered: This review will discuss the possibility to incorporate placental tissue cells in cord blood banking. It will discuss general features of human placenta, with a brief review of the immune cells at the fetal-maternal interface and the different cell populations isolated from placenta, with a particular focus on MSCs. It will address the question as to why placenta-derived MSCs should be banked with their hematopoietic counterparts. It will discuss clinical trials which are studying safety and efficacy of placenta tissue-derived MSCs in selected diseases, and preclinical studies which have proven their therapeutic properties in other diseases. It will discuss banking of umbilical cord blood and raise several issues for improvement, and the applications of cord blood cells in non-malignant disorders. Expert commentary: Umbilical cord blood banking saves lives worldwide. The concomitant banking of non-hematopoietic cells from placenta, which could be applied therapeutically in the future, alone or in combination to their hematopoietic counterparts, could exploit current banking processes while laying the foundation for clinical trials exploring placenta-derived cell therapies in regenerative medicine.

Cardiac Restoration Stemming From the Placenta Tree: Insights From Fetal and Perinatal Cell Biology

Efficient cardiac repair and ultimate regeneration still represents one of the main challenges of modern medicine. Indeed, cardiovascular disease can derive from independent conditions upsetting heart structure and performance: myocardial ischemia and infarction (MI), pharmacological cardiotoxicity, and congenital heart defects, just to name a few. All these disorders have profound consequences on cardiac tissue, inducing the onset of heart failure over time. Since the cure is currently represented by heart transplantation, which is extremely difficult due to the shortage of donors, much effort is being dedicated to developing innovative therapeutic strategies based on stem cell exploitation. Among the broad scenario of stem/progenitor cell subpopulations, fetal and perinatal sources, namely amniotic fluid and term placenta, have gained interest due to their peculiar regenerative capacity, high self-renewal capability, and ease of collection from clinical waste material. In this review, we will provide the state-of-the-art on fetal perinatal stem cells for cardiac repair and regeneration. We will discuss different pathological conditions and the main therapeutic strategies proposed, including cell transplantation, putative paracrine therapy, reprogramming, and tissue engineering approaches.

Heart Failure with Preserved Ejection Fraction and Future Pharmacological Strategies: a Glance in the Crystal Ball

PURPOSE OF REVIEW

The current definition of heart failure is mainly based on an inappropriate measure of cardiac function, i.e., left ventricular ejection fraction (LVEF). The initial sole entity, heart failure with reduced ejection fraction (HFrEF, LVEF <40%), was complemented by the addition of heart failure with preserved ejection fraction (HFpEF, LVEF ≥50%) and most recently, heart failure with mid-range ejection fraction (HFmrEF, LVEF 40-49%). Initially, HFpEF was believed to be a purely left ventricular diastolic dysfunction. Pathophysiological concepts of HFpEF have changed considerably during the last years. In addition to intrinsic cardiac mechanisms, the heart failure pathogenesis is increasingly considered as driven by non-cardiac systemic processes including metabolic disorders, ischemic conditions, and pro-inflammatory/pro-fibrotic or immunological alterations. Presentation and pathophysiology of HFpEF is heterogeneous, and its management remains a challenge since evidence of therapeutic benefits is scarce. Up to now, there are no therapies improving survival in patients with HFpEF.

RECENT FINDINGS

Several results from clinical and preclinical interventions targeting non-cardiac mechanisms or non-pharmacological interventions including new anti-diabetic or anti-inflammatory drugs, mitochondrial-targeted anti-oxidants, anti-fibrotic strategies, microRNases incl. antagomirs, cell therapeutic options, and high-density lipoprotein-raising strategies are promising and under further investigation. This review addresses mechanisms and available data of current best clinical practice and novel approaches towards HFpEF.

Placenta-derived PLX-PAD mesenchymal-like stromal cells are efficacious in rescuing blood flow in hind limb ischemia mouse model by a dose- and site-dependent mechanism of action

BACKGROUND

In peripheral artery disease (PAD), blockage of the blood supply to the limbs, most frequently the legs, leads to impaired blood flow and tissue ischemia. Pluristem's PLX-PAD cells are placenta-derived mesenchymal stromal-like cells currently in clinical trials for the treatment of peripheral artery diseases.

METHODS

In this work, the hind limb ischemia (HLI) mouse model was utilized to study the efficacy and mechanism of action of PLX-PAD cells. ELISA assays were performed to characterize and quantitate PLX-PAD secretions in vitro.

RESULTS

PLX-PAD cells administered intramuscularly rescued blood flow to the lower limb after HLI induction in a dose-dependent manner. While rescue of blood flow was site-dependent, numerous administration regimes enabled rescue of blood flow, indicating a systemic effect mediated by PLX-PAD secretions. Live PLX-PAD cells were more efficacious than cell lysate in rescuing blood flow, indicating the importance of prolonged cytokine secretion for maximal blood flow recovery. In vitro studies showed a multifactorial secretion profile including numerous pro-angiogenic proteins; these are likely involved in the PLX-PAD mechanism of action.

DISCUSSION

Live PLX-PAD cells were efficacious in rescuing blood flow after the induction of HLI in the mouse model in a dose- and site-dependent manner. The fact that various administration routes of PLX-PAD rescued blood flow indicates that the mechanism of action likely involves one of systemic secretions which promote angiogenesis. Taken together, the data support the further clinical testing of PLX-PAD cells for PAD indications.

Placenta-Derived Adherent Stromal Cells Improve Diabetes Mellitus-Associated Left Ventricular Diastolic Performance

Left ventricular (LV) diastolic dysfunction is among others attributed to cardiomyocyte stiffness. Mesenchymal stromal cells (MSC) have cardiac-protective properties. We explored whether intravenous (i.v.) application of PLacenta-eXpanded (PLX) MSC-like cells (PLX) improves LV diastolic relaxation in streptozotocin (STZ)-induced diabetic mice and investigated underlying mechanisms. Diabetes mellitus was induced by STZ application (50 mg/kg body weight) during five subsequent days. One week after the first STZ injection, PLX or saline were i.v. applied. Two weeks later, mice were hemodynamically characterized and sacrificed. At this early stage of diabetic cardiomyopathy with low-grade inflammation and no cardiac fibrosis, PLX reduced LV vascular cell adhesion molecule-1, transforming growth factor-β1, and interferon-γ mRNA expression, induced the percentage of circulating regulatory T cells, and decreased the splenic pro-fibrotic potential in STZ mice. STZ + PLX mice exhibited higher LV vascular endothelial growth factor mRNA expression and arteriole density versus STZ mice. In vitro, hyperglycemic PLX conditioned medium restored the hyperglycemia-impaired tube formation and adhesion capacity of human umbelical vein endothelial cells (HUVEC) via increasing nitric oxide (NO) bioavailability. PLX further induced the diabetes-downregulated activity of the NO downstream protein kinase G, as well as of protein kinase A, in STZ mice, which was associated with a raise in phosphorylation of the titin isoforms N2BA and N2B. Concomitantly, the passive force was lower in single isolated cardiomyocytes from STZ + PLX versus from STZ mice, which led to an improvement of LV diastolic relaxation. We conclude that i.v. PLX injection improves diabetes mellitus-associated diastolic performance via decreasing cardiomyocyte stiffness. Stem Cells Translational Medicine 2017;6:2135-2145.

Towards the standardization of stem cell therapy studies for ischemic heart diseases: Bridging the gap between animal models and the clinical setting

Today there is an increasing demand for heart transplantations for patients diagnosed with heart failure. Though, shortage of donors as well as the large number of ineligible patients hurdle such treatment option. This, in addition to the considerable number of transplant rejections, has driven the clinical research towards the field of regenerative medicine. Nonetheless, to date, several stem cell therapies tested in animal models fall by the wayside and when they meet the criteria to clinical trials, subjects often exhibit modest improvements. A main issue slowing down the admission of such therapies in the domain of human trials is the lack of protocol standardization between research groups, which hampers comparison between different approaches as well as the lack of thought regarding the clinical translation. In this sense, given the large amount of reports on stem cell therapy studies in animal models reported in the last 3years, we sought to evaluate their advantages and limitations towards the clinical setting and provide some suggestions for the forthcoming investigations. We expect, with this review, to start a new paradigm on regenerative medicine, by evoking the debate on how to plan novel stem cell therapy studies with animal models in order to achieve more consistent scientific production and accelerate the admission of stem cell therapies in the clinical setting.

Placental Stromal Cell Therapy for Experimental Autoimmune Encephalomyelitis: The Role of Route of Cell Delivery

Multiple sclerosis (MS) is an immune‐mediated disease of the central nervous system (CNS) with no effective treatment available for the chronic‐progressive stage. Cell therapy is a promising therapeutic approach for attenuating the immune‐mediated CNS process. Isolated and expanded human placental stromal cells (hPSCs) possess potent immunomodulatory and trophic properties, making them a good candidate for MS therapy. We examined the potential of hPSC therapy in preventing the onset or attenuating the course of established disease in a murine MS model of myelin oligodendrocyte glycoprotein‐induced experimental autoimmune encephalomyelitis. We examined the feasibility of hPSC systemic delivery by intramuscular (i.m.) implantation rather than the commonly used intravenous injection, which is dose‐limiting and carries the risk of pulmonary obstruction. Our findings showed significant attenuation of the disease only when hPSCs were injected directly to the central nervous system. Intramuscular implanted hPSCs survived at the site of injection for at least 2 months and elicited extensive local immune responses. Intramuscular hPSC implantation before disease onset caused a delay in the appearance of clinical signs and reduced the severity of a relapse induced by repeated challenge with the autoantigen. Intramuscular implantation after disease onset did not affect its course. Thus, pathological analysis of CNS tissue did not show inhibition of neuroinflammation in i.m. hPSC‐implanted mice. Moreover, no apparent effect was seen on the proliferative response of peripheral lymph node cells in these animals. We conclude that to maximize their therapeutic potential in MS, hPSCs should be delivered directly to the affected CNS. Stem Cells Translational Medicine2017;6:1286–1294

Mesenchymal Stromal Cells Prevent Allostimulation In Vivo and Control Checkpoints of Th1 Priming: Migration of Human DC to Lymph Nodes and NK Cell Activation

Although the immunomodulatory potency of mesenchymal stromal cells (MSC) is well established, the mechanisms behind are still not clear. The crosstalk between myeloid dendritic cells (mDC) and natural killer (NK) cells and especially NK cell-derived interferon-gamma (IFN-γ) play a pivotal role in the development of type 1 helper (Th1) cell immune responses. While many studies explored the isolated impact of MSC on either in vitro generated DC, NK, or T cells, there are only few data available on the complex interplay between these cells. Here, we investigated the impact of MSC on the functionality of human mDC and the consequences for NK cell and Th1 priming in vitro and in vivo. In critical limb ischemia patients, who have been treated with allogeneic placenta-derived mesenchymal-like stromal cells (PLX-PAD), no in vivo priming of Th1 responses toward the major histocompatibility complex (MHC) mismatches could be detected. Further in vitro studies revealed that mDC reprogramming could play a central role for these effects. Following crosstalk with MSC, activated mDC acquired a tolerogenic phenotype characterized by reduced migration toward CCR7 ligand and impaired ability to stimulate NK cell-derived IFN-γ production. These effects, which were strongly related to an altered interleukin (IL)-12/IL-10 production by mDC, were accompanied by an effective prevention of Th1 priming in vivo. Our findings provide novel evidence for the regulation of Th1 priming by MSC via modulation of mDC and NK cell crosstalk and show that off-the-shelf produced MHC-mismatched PLX-PAD can be used in patients without any sign of immunogenicity.

Immunogenicity of allogeneic mesenchymal stromal cells: what has been seen in vitro and in vivo?

Mesenchymal stromal cells (MSC) are promising candidates for supporting regeneration and suppressing undesired immune reactivity. Although autologous MSC have been most commonly used for clinical trials, data on application of allogeneic MHC-unmatched MSC were reported. The usage of MSC as an 'off-the-shelf' product would have several advantages; however, it is an immunological challenge. The preclinical studies on the (non)immunogenicity of MSC are contradictory and, unfortunately, solid data from clinical trials are missing. Induction of an alloresponse would be a major limitation for the application of allogeneic MSC. Here we discuss the key elements for the induction of an alloresponse and targets of immunomodulation by MSC as well as preclinical and clinical hints on allo(non)response to MSC.

Human placenta-derived stromal cells decrease inflammation, placental injury and blood pressure in hypertensive pregnant mice

Pre-eclampsia, the development of hypertension and proteinuria or end-organ damage during pregnancy, is a leading cause of both maternal and fetal morbidity and mortality, and there are no effective clinical treatments for pre-eclampsia aside from delivery. The development of pre-eclampsia is characterized by maladaptation of the maternal immune system, excessive inflammation and endothelial dysfunction. We have reported that detection of extracellular RNA by the Toll-like receptors (TLRs) 3 and 7 is a key initiating signal that contributes to the development of pre-eclampsia. PLacental eXpanded (PLX-PAD) cells are human placenta-derived, mesenchymal-like, adherent stromal cells that have anti-inflammatory, proangiogenic, cytoprotective and regenerative properties, secondary to paracrine secretion of various molecules in response to environmental stimulation. We hypothesized that PLX-PAD cells would reduce the associated inflammation and tissue damage and lower blood pressure in mice with pre-eclampsia induced by TLR3 or TLR7 activation. Injection of PLX-PAD cells on gestational day 14 significantly decreased systolic blood pressure by day 17 in TLR3-induced and TLR7-induced hypertensive mice (TLR3 144-111 mmHg; TLR7 145-106 mmHg; both P<0.05), and also normalized their elevated urinary protein:creatinine ratios (TLR3 5.68-3.72; TLR7 5.57-3.84; both P<0.05). On gestational day 17, aortic endothelium-dependent relaxation responses improved significantly in TLR3-induced and TLR7-induced hypertensive mice that received PLX-PAD cells on gestational day 14 (TLR3 35-65%; TLR7 37-63%; both P<0.05). In addition, markers of systemic inflammation and placental injury, increased markedly in both groups of TLR-induced hypertensive mice, were reduced by PLX-PAD cells. Importantly, PLX-PAD cell therapy had no effects on these measures in pregnant control mice or on the fetuses. These data demonstrate that PLX-PAD cell therapy can safely reverse pre-eclampsia-like features during pregnancy and have a potential therapeutic role in pre-eclampsia treatment.

In-vitro Optimization of Nanoparticle-Cell Labeling Protocols for In-vivo Cell Tracking Applications

Recent advances in theranostic nanomedicine can promote stem cell and immune cell-based therapy. Gold nanoparticles (GNPs) have been shown to be promising agents for in-vivo cell-tracking in cell-based therapy applications. Yet a crucial challenge is to develop a reliable protocol for cell upload with, on the one hand, sufficient nanoparticles to achieve maximum visibility of cells, while on the other hand, assuring minimal effect of particles on cell function and viability. Previous studies have demonstrated that the physicochemical parameters of GNPs have a critical impact on their efficient uptake by cells. In the current study we have examined possible variations in GNP uptake, resulting from different incubation period and concentrations in different cell-lines. We have found that GNPs effectively labeled three different cell-lines - stem, immune and cancer cells, with minimal impairment to cell viability and functionality. We further found that uptake efficiency of GNPs into cells stabilized after a short period of time, while GNP concentration had a significant impact on cellular uptake, revealing cell-dependent differences. Our results suggest that while heeding the slight variations within cell lines, modifying the loading time and concentration of GNPs, can promote cell visibility in various nanoparticle-dependent in-vivo cell tracking and imaging applications.

Rejuvenating effect of pregnancy on the mother

Aging is associated with reduced tissue regenerative capacity. In recent years, studies in mice have shown that transfusion of blood from young animals to old ones can reverse some aging effects and increase regenerative potential similar to that seen in young animals. Because pregnancy is a unique biological model of a partially shared blood system, we have speculated that pregnancy would have a rejuvenating effect on the mother. Recent studies support this idea. In this review, we will summarize the current knowledge of the rejuvenating effect of pregnancy on the mother.

Stem cell mechanisms during left ventricular remodeling post-myocardial infarction: Repair and regeneration

Post-myocardial infarction (MI), the left ventricle (LV) undergoes a series of events collectively referred to as remodeling. As a result, damaged myocardium is replaced with fibrotic tissue consequently leading to contractile dysfunction and ultimately heart failure. LV remodeling post-MI includes inflammatory, fibrotic, and neovascularization responses that involve regulated cell recruitment and function. Stem cells (SCs) have been transplanted post-MI for treatment of LV remodeling and shown to improve LV function by reduction in scar tissue formation in humans and animal models of MI. The promising results obtained from the application of SCs post-MI have sparked a massive effort to identify the optimal SC for regeneration of cardiomyocytes and the paradigm for clinical applications. Although SC transplantations are generally associated with new tissue formation, SCs also secrete cytokines, chemokines and growth factors that robustly regulate cell behavior in a paracrine fashion during the remodeling process. In this review, the different types of SCs used for cardiomyogenesis, markers of differentiation, paracrine factor secretion, and strategies for cell recruitment and delivery are addressed.

Association of serum periostin with cardiac function and short-term prognosis in acute myocardial infarction patients

Background

Periostin was proved to play an important role in extra-cellular matrix remodeling after acute myocardial infarction (AMI). Myocardial periostin was markedly up-regulated after AMI and participated in the maladaptive process of cardiac remodeling. However, few researches focused on the circulating periostin and its significance. This study aims to investigate the association of serum periostin level with cardiac function and short-term prognosis in AMI patients.

Methodology/Principal Findings

We totally recruited 50 patients diagnosed as ST-elevation myocardial infarction. Blood samples were taken within 12 hours after the onset of AMI before emergency coronary revascularization procedures. Serum periostin was measured using enzyme-linked immunosorbent assay. All patients received echocardiography examination within one week after hospitalization. Correlations of serum periostin with echocardiography parameters, Killip class and myocardium injury biomarkers (CK-MB/troponin T) were investigated. AMI patients were divided into two groups by serum periostin level (higher/lower periostin group) and followed up for six months. Primary endpoints included cardiovascular mortality, nonfatal stroke/transient ischemic attack, chest pain occurrence and re-hospitalization. Secondary endpoint referred to composite cardiovascular events including all the primary endpoints.

Result

Serum periostin was in negative association with left ventricular ejection fraction (LVEF) (r = −0.472, *p<0.01) and left atrium diameter (LAD) (r = −0.328, *p<0.05). Positive correlation was found between serum periostin level and Killip class (r = 0.395, *p<0.01). There was no association between serum periostin and CK-MB or troponin T (p>0.05). After six months follow up, patients in higher periostin group showed increased composite cardiovascular events (*p<0.05). Patients showed no significant difference in primary endpoints between the two groups.

Conclusions/Significance

Serum periostin was in negative correlation with LVEF and LAD, in positive association with Killip class and higher serum periostin level may be predictive for worse short-term disease prognosis indicated as more composite cardiovascular events six months post AMI.

Epithelial-to-Mesenchymal Transition Enhances the Cardioprotective Capacity of Human Amniotic Epithelial Cells

The amniotic epithelium consists of cells exhibiting mature epithelial cell characteristics, but also varying degrees of stemness. We tested the hypothesis that induction of epithelial-to-mesenchymal transition (EMT) in amniotic epithelial cells (AECs) derived from human placenta enhances their capacity to support the ischemic myocardium. In response to incubation with transforming growth factor-β1 (TGF-β1) protein, AECs lost their cobblestone morphology and acquired a fibroblastoid shape, associated with downregulation of E-cadherin, upregulation of N-cadherin, Akt phosphorylation, and intracellular periostin translocation. EMT-AECs displayed greatly enhanced mobility and secreted gelatinase activity compared with naive AECs. The surface presentation of CD105 and CD73 decreased, and RNA microarray analysis mirrored the loss of epithelial characteristics and transcriptional profile. Unmodified AECs and EMT-AECs were then injected intramyocardially in fully immunocompetent mice after permanent LAD ligation, and heart function was followed by MRI as well as 2D speckle tracking echocardiography after 4 weeks. EMT-AEC-treated infarct hearts displayed better global systolic function and improved longitudinal strain rate in the area of interest. Although no signals of human cells were detectable by histology, infarct size was smaller in EMT-AEC-treated hearts, associated with fewer TUNEL-positive cells and upregulation of periostin, while blood vessel density was increased in both ACE- and EMT-AEC-treated hearts. We conclude that EMT enhances the cardioprotective effects of human AECs.