For several decades, multipotent mesenchymal stromal cells (MSCs) have been extensively studied for their therapeutic potential across a wide range of diseases. In the preclinical setting, MSCs demonstrate consistent ability to promote tissue healing, down-regulate excessive inflammation and improve outcomes in animal models. Several proposed mechanisms of action have been posited and demonstrated across an array of in vitro models. However, translation into clinical practice has proven considerably more difficult. A number of prominent well-funded late-phase clinical trials have failed, thus calling out for new efforts to optimize product delivery in the clinical setting. In this review, we discuss novel topics critical to the successful translation of MSCs from pre-clinical to clinical applications. In particular, we focus on the major routes of cell delivery, aspects related to hemocompatibility, and potential safety concerns associated with MSC therapy in the different settings.

Traumatic brain injury (TBI) is soon predicted to become the third leading cause of death and disability worldwide. After the primary injury, a complex set of secondary injuries develops hours and days later with prolonged neuroinflammation playing a key role. TBI and other inflammatory conditions are currently being treated in preclinical and clinical trials by a number of cellular therapies. Mesenchymal stem cells (MSC) are of great interest due to their widespread usage, safety, and relative ease to isolate and culture. However, there has been a wide range in efficacy reported using MSC clinically and in preclinical models, likely due to differences in cell preparations and a significant amount of donor variability. In this study, we seek to find a correlation between in vitro activity and in vivo efficacy. We designed assays to explore the responsiveness of MSC to immunological cues to address the immunomodulatory properties of MSC, one of their primary modes of therapeutic activity in TBI. Our results showed intrinsic differences in the immunomodulatory capacity of MSC preparations from different bone marrow and amniotic fluid donors. This difference mirrored the therapeutic capacity of the MSC in an experimental model of TBI, an effect confirmed using siRNA knockdown of COX2 followed by overexpressing COX2. Among the immunomodulatory factors assessed, the therapeutic benefit correlated with the secretion of prostaglandin E2 (PGE ) by MSC prior to treatment, suggesting that measurement of PGE could be a very useful potency marker to create an index of predicted efficacy for preparations of MSC to treat TBI. Stem Cells 2017;35:1416-1430.

Background Numerous pre-clinical studies using bone marrow derived cells for the treatment of traumatic brain injury and stroke have demonstrated efficacy in terms of blood-brain barrier preservation, neurogenesis, and other functional outcomes. Phase 1 clinical trials using bone marrow mononuclear cells infused intravenously in children with severe TBI demonstrated safety and potentially a CNS structural preservation treatment effect. This study sought to confirm the safety, logistic feasibility, and potential treatment effect size of structural preservation/inflammatory biomarker mitigation in adults to guide Phase 2 clinical trial design. Methods Adults (aged 18-55) with severe traumatic brain injury (GCS 5-8) and without signs of serious other injury or irreversible brain injury (see Table 1) were evaluated for entry into the trial. A dose escalation format was performed in 25 patients: 5 controls, followed 5 patients in each dosing cohort (6,9,12 ×106 cells/kg body weight), then 5 more controls. Bone marrow harvest, cell processing to isolate the mononuclear fraction, and re-infusion occurred within 48 hours after injury. Patients were monitored for harvest/infusion related hemodynamic changes, infusional toxicity, and adverse events. Outcome measures included MRI based measurements of supratentorial and corpus callosal volumes as well as DTI based measurements of fractional anisotropy and mean diffusivity of the corpus callosum and the corticospinal tract at the level of the brainstem at 1 month and 6 months post-injury. Functional and neurocognitive outcomes were measured and correlated with imaging data. Inflammatory cytokine arrays were measured in the plasma pre-treatment, post-treatment, and at 1 and 6 month follow-up. Results There were no serious adverse events related to harvest/infusion. There was a mild pulmonary toxicity of the highest dose that was not clinically significant. Despite the treatment group having greater injury severity, there was structural preservation of critical regions of interest that correlated with functional outcomes. Key inflammatory cytokines were down-regulated after BMMNC infusion. Conclusions Treatment of severe, adult traumatic brain injury using an intravenously delivered autologous bone marrow mononuclear cell infusion is safe and logistically feasible. There appears to be a treatment signal as evidenced by CNS structural preservation, consistent with previous pediatric trial data. Inflammatory biomarkers are down-regulated after cell infusion. A Phase 2, prospective, randomized trial excluding the highest dose is warranted and can be powered based upon structural outcome variables.

Although hepatic cell transplantation (CT) holds the promise of bridging patients with end-stage chronic liver failure to whole liver transplantation, suitable cell populations are under debate. In addition to hepatic cells, mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs) are being considered as alternative cell sources for initial clinical cell work. Fetal liver (FL) tissue contains potential progenitors for all these cell lineages. Based on the collagenase incubation of tissue fragments, traditional isolation techniques yield only a fraction of the number of available cells. We report a 5-step method in which a portal vein in situ perfusion technique is used for tissue from the late second trimester. This method results in the high viabilities known for adult liver vascular perfusion, addresses the low cell yields of conventional digestion methods, and reduces the exposure of the tissue to collagenase 4-fold. We used donated tissue from gestational weeks 18 to 22, Additional Supporting Information may be found in the online version of this article.

The parameters which influence the self-assembly of molecules in solution include the temperature and solvent quality, and this study illustrates the use of these variables to regulate the degree of association of block copolymer amphiphiles in highly compressible supercritical carbon dioxide. Small-angle neutron scattering (SANS) has been used to examine the association behavior of a block copolymer containing a CO2-phobic moiety, poly(vinyl acetate), and a CO2-philic block, poly(1,1-dihydroperfluoro-octylacrylate). By adjustment of the density of the medium through pressure and temperature profiling, the self-assembly can be reversibly controlled from unimers to core-shell spherical micelles and this establishes a critical micelle density (CMD), a phenomenon distinctive of highly compressible fluids, such as supercritical CO2. Mathematical modeling of the data in terms of core-shell micelle structures permits a detailed description of the structure and the degree of swelling (penetration) of the solvent into the different regions of the aggregates throughout this transition.