Standardization of cellular therapy terminology, coding and labeling: a review.

The 1990s saw rapid growth in international activity in hematopoietic cell transplantation. As national donor registries were established and international collaboration increased, a need to transfer cellular therapy products across national borders emerged. A lack of international standards for identification, terminology and labeling resulted in significant challenges for import and export. Twenty years of effort by a large group of experts supported by professional societies and accreditation bodies has today achieved a high degree of standardization. This review highlights the main landmarks in this journey and serves as a reminder of the importance of taking the "long view" when working toward international standardization. It demonstrates the need for continual maintenance and enhancement of standards to meet the changing needs of the cell therapy industry and highlights recent developments in ISBT 128.

Advanced therapy medicinal product manufacturing under the hospital exemption and other exemption pathways in seven European Union countries.

BACKGROUND AIMS: As part of the advanced therapy medicinal product (ATMP) regulation, the hospital exemption (HE) was enacted to accommodate manufacturing of custom-made ATMPs for treatment purposes in the European Union (EU). However, how the HE pathway has been used in practice is largely unknown. METHODS: Using a survey and interviews, we provide the product characteristics, scale and motivation for ATMP manufacturing under HE and other, non-ATMP-specific exemption pathways in seven European countries. RESULTS: Results show that ATMPs were manufactured under HE by public facilities located in Finland, Germany, Italy and the Netherlands, which enabled availability of a modest number of ATMPs (n = 12) between 2009 and 2017. These ATMPs were shown to have close proximity to clinical practice, and manufacturing was primarily motivated by clinical needs and clinical experience. Public facilities used HE when patients could not obtain treatment in ongoing or future trials. Regulatory aspects motivated (Finland, Italy, the Netherlands) or limited (Belgium, Germany) HE utilization, whereas financial resources generally limited HE utilization by public facilities. Public facilities manufactured other ATMPs (n = 11) under named patient use (NPU) between 2015 and 2017 and used NPU in a similar fashion as HE. The scale of manufacturing under HE over 9 years was shown to be rather limited in comparison to manufacturing under NPU over 3 years. In Germany, ATMPs were mainly manufactured by facilities of private companies under HE. CONCLUSIONS: The HE enables availability of ATMPs with close proximity to clinical practice. Yet in some countries, HE provisions limit utilization, whereas commercial developments could be undermined by private HE licenses in Germany. Transparency through a public EU-wide registry and guidance for distinguishing between ATMPs that are or are not commercially viable as well as public-private engagements are needed to optimize the use of the HE pathway and regulatory pathways for commercial development in a complementary fashion.

Phase I/II open-label trial of intravenous allogeneic mesenchymal stromal cell therapy in adults with recessive dystrophic epidermolysis bullosa.

BACKGROUND: Recessive dystrophic epidermolysis bullosa (RDEB) is a hereditary blistering disorder due to a lack of type VII collagen. At present, treatment is mainly supportive. OBJECTIVES: To determine whether intravenous allogeneic bone marrow-derived mesenchymal stromal/stem cells (BM-MSCs) are safe in RDEB adults and if the cells improve wound healing and quality of life. METHODS: We conducted a prospective, phase I/II, open-label study recruiting 10 RDEB adults to receive 2 intravenous infusions of BM-MSCs (on day 0 and day 14; each dose 2-4 × 106 cells/kg). RESULTS: BM-MSCs were well tolerated with no serious adverse events to 12 months. Regarding efficacy, there was a transient reduction in disease activity scores (8/10 subjects) and a significant reduction in itch. One individual showed a transient increase in type VII collagen. LIMITATIONS: Open-label trial with no placebo. CONCLUSIONS: MSC infusion is safe in RDEB adults and can have clinical benefits for at least 2 months.

Bone-marrow derived mesenchymal stromal cells infusion in therapy refractory juvenile idiopathic arthritis patients.

OBJECTIVES: To compare the total number of adverse events (AEs) before and after mesenchymal stromal cell (MSC) infusion in refractory JIA and to evaluate its effectiveness. METHODS: Single-centre Proof of Mechanism Phase Ib, open label intervention study in JIA patients previously failing all biologicals registered for their diagnosis. Six patients received 2 million/kg intravenous infusions of allogeneic bone-marrow derived MSC. In case of ACR-Ped30-response but subsequent loss of response one and maximal two repeated infusions are allowed. RESULTS: Six JIA patients with 9.2 years median disease duration, still active arthritis and damage were included. All had failed methotrexate, corticosteroids and median five different biologicals. MSC were administered twice in three patients. No acute infusion reactions were observed and a lower post-treatment than pre-treatment incidence in AEs was found. The one systemic onset JIA (sJIA) patient had again an evolving macrophage activation syndrome, 9 weeks after tocilizumab discontinuation and 7 weeks post-MSC infusion. Statistically significant decreases were found 8 weeks after one MSC infusion in VAS well-being (75-56), the JADAS-71 (24.5-11.0) and the cJADAS10 (18.0-10.6). CONCLUSION: MSC infusions in six refractory JIA patients were safe, although in sJIA stopping the 'failing' biologic treatment carries a risk of a MAS flare, as the drug might still suppress the systemic features. TRIAL REGISTRATION: Trial register.nl, http://https://www.trialregister.nl, NTR4146.

Allogeneic MSCs and Recycled Autologous Chondrons Mixed in a One-Stage Cartilage Cell Transplantion: A First-in-Man Trial in 35 Patients.

MSCs are known as multipotent mesenchymal stem cells that have been found capable of differentiating into various lineages including cartilage. However, recent studies suggest MSCs are pericytes that stimulate tissue repair through trophic signaling. Aimed at articular cartilage repair in a one-stage cell transplantation, this study provides first clinical evidence that MSCs stimulate autologous cartilage repair in the knee without engrafting in the host tissue. A phase I (first-in-man) clinical trial studied the one-stage application of allogeneic MSCs mixed with 10% or 20% recycled defect derived autologous chondrons for the treatment of cartilage defects in 35 patients. No treatment-related serious adverse events were found and statistically significant improvement in clinical outcome shown. Magnetic resonance imaging and second-look arthroscopies showed consistent newly formed cartilage tissue. A biopsy taken from the center of the repair tissue was found to have hyaline-like features with a high concentration of proteoglycans and type II collagen. DNA short tandem repeat analysis delivered unique proof that the regenerated tissue contained patient-DNA only. These findings support the hypothesis that allogeneic MSCs stimulate a regenerative host response. This first-in-man trial supports a paradigm shift in which MSCs are applied as augmentations or "signaling cells" rather than differentiating stem cells and opens doors for other applications. Stem Cells 2017;35:1984-1993.

Allogeneic Mesenchymal Stem Cells Stimulate Cartilage Regeneration and Are Safe for Single-Stage Cartilage Repair in Humans upon Mixture with Recycled Autologous Chondrons.

Traditionally, mesenchymal stem cells (MSCs) isolated from adult bone marrow were described as being capable of differentiating to various lineages including cartilage. Despite increasing interest in these MSCs, concerns regarding their safety, in vivo behavior and clinical effectiveness have restrained their clinical application. We hypothesized that MSCs have trophic effects that stimulate recycled chondrons (chondrocytes with their native pericellular matrix) to regenerate cartilage. Searching for a proof of principle, this phase I (first-in-man) clinical trial applied allogeneic MSCs mixed with either 10% or 20% recycled autologous cartilage-derived cells (chondrons) for treatment of cartilage defects in the knee in symptomatic cartilage defect patients. This unique first in man series demonstrated no treatment-related adverse events up to one year postoperatively. At 12 months, all patients showed statistically significant improvement in clinical outcome compared to baseline. Magnetic resonance imaging and second-look arthroscopies showed completely filled defects with regenerative cartilage tissue. Histological analysis on biopsies of the grafts indicated hyaline-like regeneration with a high concentration of proteoglycans and type II collagen. Short tandem repeat analysis showed the regenerative tissue only contained patient-own DNA. These findings support the novel insight that the use of allogeneic MSCs is safe and opens opportunities for other applications. Stem cell-induced paracrine mechanisms may play an important role in the chondrogenesis and successful tissue regeneration found. Stem Cells 2017;35:256-264.

Effect of repetitive intra-arterial infusion of bone marrow mononuclear cells in patients with no-option limb ischemia: the randomized, double-blind, placebo-controlled Rejuvenating Endothelial Progenitor Cells via Transcutaneous Intra-arterial Supplementation (JUVENTAS) trial.

BACKGROUND: Patients with severe limb ischemia may not be eligible for conventional therapeutic interventions. Pioneering clinical trials suggest that bone marrow-derived cell therapy enhances neovascularization, improves tissue perfusion, and prevents amputation. The objective of this trial was to determine whether repetitive intra-arterial infusion of bone marrow mononuclear cells (BMMNCs) in patients with severe, nonrevascularizable limb ischemia can prevent major amputation. METHODS AND RESULTS: The Rejuvenating Endothelial Progenitor Cells via Transcutaneous Intra-arterial Supplementation (JUVENTAS) trial is a randomized, double-blind, placebo-controlled clinical trial in 160 patients with severe, nonrevascularizable limb ischemia. Patients were randomly assigned to repetitive (3 times; 3-week interval) intra-arterial infusion of BMMNC or placebo. No significant differences were observed for the primary outcome, ie, major amputation at 6 months, with major amputation rates of 19% in the BMMNC versus 13% in the placebo group (relative risk, 1.46; 95% confidence interval, 0.62-3.42). The safety outcome (all-cause mortality, occurrence of malignancy, or hospitalization due to infection) was not significantly different between the groups (relative risk, 1.46; 95% confidence interval, 0.63-3.38), neither was all-cause mortality at 6 months with 5% versus 6% (relative risk, 0.78; 95% confidence interval, 0.22-2.80). Secondary outcomes quality of life, rest pain, ankle-brachial index, and transcutaneous oxygen pressure improved during follow-up, but there were no significant differences between the groups. CONCLUSIONS: Repetitive intra-arterial infusion of autologous BMMNCs into the common femoral artery did not reduce major amputation rates in patients with severe, nonrevascularizable limb ischemia in comparison with placebo. The general improvement in secondary outcomes during follow-up in both the BMMNC and the placebo group, as well, underlines the essential role for placebo-controlled design of future trials. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00371371.

Core diameter of bone marrow aspiration devices influences cell density of bone marrow aspirate in patients with severe peripheral artery disease.

BACKGROUND AIMS: Bone marrow (BM) transplantations are an accepted therapeutic strategy for hematologic conditions. In the past decades, interest for BM-derived cell therapy has extended toward the field of regenerative medicine. Irrespective of the treatment strategy, its success depends on the amount of cells available for transplantation. Both patient and procedural factors have been shown to influence the cell density of the BM aspirate. In the present study, the influence of core diameter of the BM aspiration device on cell density of the BM aspirate is studied. METHODS: BM harvesting procedures performed in a clinical trial investigating the effect of BM cell therapy in patients with severe peripheral artery disease were retrospectively studied (clinicaltrials.gov NCT00371371). Patients underwent BM harvesting through the use of either a 15-gauge (n = 85) or an 8-gauge (n = 75) needle. The numbers of harvested white blood cells (WBC) and CD34(+) hematopoietic cells (HPC) were quantified. RESULTS: The amount of WBC per milliliter of BM aspirate was significantly higher when the 8-gauge needle (27.8 × 10(6) WBC/mL [95%CI 25.4-30.5 × 10(6)]) was used compared with the smaller 15-gauge core needle (20.1 × 10(6) WBC/mL [95% confidence interval (CI), 18.7-21.7 × 10(6)], P < 0.001). For the amount of CD34(+) HPC, a similar pattern was observed (185 × 10(3) HPC/mL [95% CI, 161-213 × 10(3)]; 114 × 10(3) HPC/mL [95% CI, 96-134 × 10(3)]; P < 0.001). CONCLUSIONS: The application of a BM aspiration device with a larger core diameter is associated with an increased cell density of the BM aspiration product in patients with severe peripheral artery disease.

Training practices of cell processing laboratory staff: analysis of a survey by the Alliance for Harmonization of Cellular Therapy Accreditation.

BACKGROUND AIMS: Methods for processing products used for hematopoietic progenitor cell (HPC) transplantation must ensure their safety and efficacy. Personnel training and ongoing competency assessment is critical to this goal. Here we present results from a global survey of methods used by a diverse array of cell processing facilities for the initial training and ongoing competency assessment of key personnel. METHODS: The Alliance for Harmonisation of Cellular Therapy Accreditation (AHCTA) created a survey to identify facility type, location, activity, personnel, and methods used for training and competency. A survey link was disseminated through organizations represented in AHCTA to processing facilities worldwide. Responses were tabulated and analyzed as a percentage of total responses and as a percentage of response by region group. RESULTS: Most facilities were based at academic medical centers or hospitals. Facilities with a broad range of activity, product sources and processing procedures were represented. Facilities reported using a combination of training and competency methods. However, some methods predominated. Cellular sources for training differed for training versus competency and also differed based on frequency of procedures performed. Most facilities had responsibilities for procedures in addition to processing for which training and competency methods differed. Although regional variation was observed, training and competency requirements were generally consistent. CONCLUSIONS: Survey data showed the use of a variety of training and competency methods but some methods predominated, suggesting their utility. These results could help new and established facilities in making decisions for their own training and competency programs.

ISBT 128 coding and labeling for cellular therapy products.

This paper describes the development of the ISBT 128 coding and labeling for cellular therapy products. It is published on behalf of the international Cellular Therapy Coding and Labeling Advisory Group (see www.ICCBBA.org ).

Current Regulations for the Production of Multipotent Mesenchymal Stromal Cells for Clinical Application.

SUMMARY: In this review, the appropriate legislation on the expansion of multipotent mesenchymal stromal cells (MSCs) in Europe is described. The collection of cells and the manufacturing of MSCs are being regulated by European Directives (EUDs). Recently, the Regulation on Advanced Therapies Medicinal Products (ATMPs) is being published, which is of importance for the production of MSCs in Europe, and this legislation is not yet ready, but it is in its final stage. MSCs are currently being used in clinical trials, mostly in academic hospitals, for patients suffering from a wide variety of diseases. Companies (small and medium-sized enterprises) are becoming more and more involved in the production of MSCs for human use, and since marketing authorisation is the scope of the Regulation it was decided to install a Committee on Advanced Therapies (CAT) within European Medicines Agency (EMEA). This CAT will formulate a draft opinion on quality, safety and efficacy of ATMPs and will have an advisory and scientific role for the Committee for Medicinal Products for human use. The aim of this review is to outline the current legislation which is important for the manufacturing of MSCs.

A randomized multicenter comparison of CD34(+)-selected progenitor cells from blood vs from bone marrow in recipients of HLA-identical allogeneic transplants for hematological malignancies.

OBJECTIVE: Peripheral blood progenitor cells (PBPC) have been established as an alternative source of hematopoietic stem cells for allogeneic transplantation, but an increased incidence of both acute and chronic graft-vs-host disease (GVHD) has become apparent. We performed a prospective randomized trial comparing bone marrow transplantation (BMT) vs PBPC transplantation (PBPCT) using CD34(+) selection for T-cell depletion (TCD) in both study arms. PATIENTS AND METHODS: Between January 1996 and October 2000, 120 patients with a diagnosis of acute leukemia, myelodysplasia, multiple myeloma, or lymphoma were randomized to receive either filgrastim-mobilized PBPC or BM from HLA-identical sibling donors after standard high-dose chemoradiotherapy. Patient characteristics did not differ between study arms. RESULTS: Recipients of PBPC received more CD3(+) T cells (median: 3.0 vs 2.0 x 10(5)/kg, p<0.0001) and more CD34(+) cells (median: 3.6 vs 0.9 x 10(6)/kg, p<0.0001). Neutrophil and platelet recoveries occurred significantly faster after PBPCT. The cumulative incidence of acute GVHD grades II-IV was 37% after BMT vs 52% after PBPCT and was most significantly (p=0.007) affected by the number of CD3(+) T cells in the graft. Acute GVHD appeared strongly associated with increased treatment-related mortality (TRM) in a time-dependent analysis. Higher numbers of CD34(+) cells were associated with less TRM. With a median follow-up of 37 months (range: 12-75), overall survival at 4 years from transplantation was 60% after BMT and 34% for recipients of PBPCT (p=0.04), which difference was largely due to increased GVHD and TRM in PBPC recipients receiving T-cell dosages greater than 2 x 10(5)/kg. CONCLUSION: Outcome following T cell-depleted PBPCT critically depends on the number of CD3(+) T cells, whereby high T-cell numbers may blunt a favorable effect of higher CD34(+) cell numbers.

Autologous, allogeneic, induced pluripotent stem cell or a combination stem cell therapy? Where are we headed in cartilage repair and why: a concise review.

The evolution of articular cartilage repair procedures has resulted in a variety of cell-based therapies that use both autologous and allogeneic mesenchymal stromal cells (MSCs). As these cells are increasingly available and show promising results both in vitro and in vivo, cell-based strategies, which aim to improve ease of use and cost-effectiveness, are progressively explored. The use of MSCs in cartilage repair makes it possible to develop single-stage cell-based therapies. However, true single-stage procedures rely on one intervention, which will limit cell sources to fraction concentrates containing autologous MSCs or culture-expanded allogeneic MSCs. So far, it seems both autologous and allogeneic cells can safely be applied, but clinical studies are still ongoing and little information on clinical outcome is available. Further development of cell-based therapies may lead to clinical-grade, standardized, off-the-shelf products with easy handling for orthopedic surgeons. Although as of yet no preclinical or clinical studies are ongoing which explore the use of induced pluripotent stem cells for cartilage repair, a good manufacturing practice-grade induced pluripotent stem cell line might become the basis for such a product in the future, providing that cell fate can be controlled. The use of stem cells in clinical trials brings along new ethical issues, such as proper controls and selecting primary outcome measures. More clinical trials are needed to estimate detailed risk-benefit ratios and trials must be carefully designed to minimize risks and burdens for patients while choosing outcome measures that allow for adequate comparison with results from similar trials. In this review, we discuss the different aspects of new stem cell-based treatments, including safety and ethical issues, as well as provide an overview of current clinical trials exploring these approaches and future perspectives.

Untouched GMP-Ready Purified Engineered Immune Cells to Treat Cancer.

PURPOSE: Engineering T cells with receptors to redirect the immune system against cancer has most recently been described as a scientific breakthrough. However, a main challenge remains the GMP-grade purification of immune cells selectively expressing the introduced receptor in order to reduce potential side effects due to poorly or nonengineered cells. EXPERIMENTAL DESIGN: In order to test a novel purification strategy, we took advantage of a model γδT cell receptor (TCR), naturally interfering with endogenous TCR expression and designed the optimal retroviral expression cassette to achieve maximal interference with endogenous TCR chains. Following retroviral transduction, nonengineered and poorly engineered immune cells characterized by a high endogenous αßTCR expression were efficiently depleted with GMP-grade anti-αßTCR beads. Next, the engineered immune cells were validated for TCR expression, function against a panel of tumor cell lines and primary tumors and potential allo-reactivity. Engineered immune cells were further validated in two humanized mouse tumor models. RESULTS: The untouched enrichment of engineered immune cells translated into highly purified receptor-engineered cells with strong antitumor reactivity both in vitro and in vivo. Importantly, this approach eliminated residual allo-reactivity of engineered immune cells. Our data demonstrate that even with long-term suboptimal interference with endogenous TCR chains such as in resting cells, allo-reactivity remained absent and tumor control preserved. CONCLUSIONS: We present a novel enrichment method for the production of untouched engineered immune cells, ready to be translated into a GMP-grade method and potentially applicable to all receptor-modified cells even if interference with endogenous TCR chains is far from complete.

Direct Cell-Cell Contact with Chondrocytes Is a Key Mechanism in Multipotent Mesenchymal Stromal Cell-Mediated Chondrogenesis.

Using a combination of articular chondrocytes (ACs) and mesenchymal stromal cells (MSCs) has shown to be a viable option for a single-stage cell-based treatment of focal cartilage defects. However, there is still considerable debate whether MSCs differentiate or have a chondroinductive role through trophic factors. In addition, it remains unclear whether direct cell-cell contact is necessary for chondrogenesis. Therefore, the aim of this study was to investigate whether direct or indirect cell-cell contact between ACs and MSCs is essential for increased cartilage production in different cellular environments and elucidate the mechanisms behind these cellular interactions. Human ACs and MSCs were cultured in a 10:90 ratio in alginate beads, fibrin scaffolds, and pellets. Cells were mixed in direct cocultures, separated by a Transwell filter (indirect cocultures), or cultured with conditioned medium. Short tandem repeat analysis revealed that the percentages of ACs increased during culture, while those of MSCs decreased, with the biggest change in fibrin glue scaffolds. For alginate, where the lack of cell-cell contact could be confirmed by histological analysis, no difference was found in matrix production between direct and indirect cocultures. For fibrin scaffolds and pellet cultures, an increased glycosaminoglycan production and type II collagen deposition were found in direct cocultures compared with indirect cocultures and conditioned medium. Positive connexin 43 staining and transfer of cytosolic calcein indicated communication through gap junctions in direct cocultures. Taken together, these results suggest that MSCs stimulate cartilage formation when placed in close proximity to chondrocytes and that direct cell-cell contact and communication through gap junctions are essential in this chondroinductive interplay.

Applying extracellular vesicles based therapeutics in clinical trials - an ISEV position paper.

Extracellular vesicles (EVs), such as exosomes and microvesicles, are released by different cell types and participate in physiological and pathophysiological processes. EVs mediate intercellular communication as cell-derived extracellular signalling organelles that transmit specific information from their cell of origin to their target cells. As a result of these properties, EVs of defined cell types may serve as novel tools for various therapeutic approaches, including (a) anti-tumour therapy, (b) pathogen vaccination, (c) immune-modulatory and regenerative therapies and (d) drug delivery. The translation of EVs into clinical therapies requires the categorization of EV-based therapeutics in compliance with existing regulatory frameworks. As the classification defines subsequent requirements for manufacturing, quality control and clinical investigation, it is of major importance to define whether EVs are considered the active drug components or primarily serve as drug delivery vehicles. For an effective and particularly safe translation of EV-based therapies into clinical practice, a high level of cooperation between researchers, clinicians and competent authorities is essential. In this position statement, basic and clinical scientists, as members of the International Society for Extracellular Vesicles (ISEV) and of the European Cooperation in Science and Technology (COST) program of the European Union, namely European Network on Microvesicles and Exosomes in Health and Disease (ME-HaD), summarize recent developments and the current knowledge of EV-based therapies. Aspects of safety and regulatory requirements that must be considered for pharmaceutical manufacturing and clinical application are highlighted. Production and quality control processes are discussed. Strategies to promote the therapeutic application of EVs in future clinical studies are addressed.

Development and application of quantitative real time PCR and RT-PCR assays that discriminate between the full-length and truncated herpes simplex virus thymidine kinase gene.

Allogeneic donor T lymphocytes manipulated genetically to express the herpes simplex virus thymidine kinase (HSV-TK) gene have emerged as promising tools to alter the balance between graft versus host disease and graft versus leukemia after allogeneic stem cell transplantation, since they can be eliminated selectively in vivo with ganciclovir. Recently, it was reported that in SFCMM-3, an HSV-TK-encoding retroviral vector, two cryptic splice sites in the HSV-TK sequence led to the generation of an HSV-TK splice variant (deltaHSV-TK) that encodes a ganciclovir-resistant gene product. In order to quantify wtHSV-TK and deltaHSV-TK RNA levels we have developed two real time Taqman PCR assays. We demonstrate that the sensitivity of both PCR assays is 10(-4). It was found that the splice variant is generated in the packaging cell line and results in approximately 4.8+/-1.9% of virions that contain deltaHSV-TK RNA. After transduction of human T cells no significant increase in deltaHSV-TK RNA could be detected. Thus, at maximum 4.2+/-1.2% of T cells transduced with SFCMM-3 will be resistant to ganciclovir due to this mechanism only. Together, these assays provide a powerful method to monitor patients in future clinical trials.

Intranasal administration of human MSC for ischemic brain injury in the mouse: in vitro and in vivo neuroregenerative functions.

Intranasal treatment with C57BL/6 MSCs reduces lesion volume and improves motor and cognitive behavior in the neonatal hypoxic-ischemic (HI) mouse model. In this study, we investigated the potential of human MSCs (hMSCs) to treat HI brain injury in the neonatal mouse. Assessing the regenerative capacity of hMSCs is crucial for translation of our knowledge to the clinic. We determined the neuroregenerative potential of hMSCs in vitro and in vivo by intranasal administration 10 d post-HI in neonatal mice. HI was induced in P9 mouse pups. 1×10(6) or 2×10(6) hMSCs were administered intranasally 10 d post-HI. Motor behavior and lesion volume were measured 28 d post-HI. The in vitro capacity of hMSCs to induce differentiation of mouse neural stem cell (mNSC) was determined using a transwell co-culture differentiation assay. To determine which chemotactic factors may play a role in mediating migration of MSCs to the lesion, we performed a PCR array on 84 chemotactic factors 10 days following sham-operation, and at 10 and 17 days post-HI. Our results show that 2×10(6) hMSCs decrease lesion volume, improve motor behavior, and reduce scar formation and microglia activity. Moreover, we demonstrate that the differentiation assay reflects the neuroregenerative potential of hMSCs in vivo, as hMSCs induce mNSCs to differentiate into neurons in vitro. We also provide evidence that the chemotactic factor CXCL10 may play an important role in hMSC migration to the lesion site. This is suggested by our finding that CXCL10 is significantly upregulated at 10 days following HI, but not at 17 days after HI, a time when MSCs no longer reach the lesion when given intranasally. The results described in this work also tempt us to contemplate hMSCs not only as a potential treatment option for neonatal encephalopathy, but also for a plethora of degenerative and traumatic injuries of the nervous system.