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Although the treatment paradigm for chronic lymphocytic leukemia (CLL) is rapidly changing, the disease remains incurable, except with allogeneic bone marrow transplantation, and resistance, relapsed disease, and partial responses persist as significant challenges. Recent studies have uncovered roles for epigenetic modification in the regulation of mechanisms contributing to malignant progression of CLL B cells. However, the extent to which epigenetic modifiers can be targeted for therapeutic benefit in CLL patients remains poorly explored. We report for the first time that expression of epigenetic modifier histone deacetylase 6 (HDAC6) is upregulated in CLL patient samples, cell lines, and euTCL1 transgenic mouse models compared with HDAC6 in normal controls. Genetic silencing of HDAC6 conferred survival benefit in euTCL1 mice. Administration of isoform-specific HDAC6 inhibitor ACY738 in the euTCL1 aging and adoptive transfer models deterred proliferation of CLL B cells, delayed disease onset via disruption of B-cell receptor signaling, and sensitized CLL B cells to apoptosis. Furthermore, coadministration of ACY738 and ibrutinib displayed synergistic cell kill against CLL cell lines and improved overall survival compared with either single agent in vivo. These results demonstrate for the first time the therapeutic efficacy of selective HDAC6 inhibition in preclinical CLL models and suggest a rationale for the clinical development of HDAC6 inhibitors for CLL treatment, either alone or in combination with Bruton tyrosine kinase inhibition.

Stroke is a significant unmet clinical need. The current stroke treatment of tissue plasminogen activator is limited to the very acute 4.5 h after disease onset which benefits only less than 3% of ischemic stroke patients. Our overarching hypothesis advances the notion that gender, which has been established as a comorbidity factor of stroke, plays a key role in regenerative medicine, in particular stem cell therapy. We hypothesize that gender is a key factor in culture-induced stemness of adult stem cells. Our goal is to provide new evidence supporting gender effects on stroke and stem cells for the purpose of enhancing our understanding of the pathophysiology of the disease and developing novel stem cell-based therapeutics targeting gender-relevant stress hormones as manifested in a stroke-postpartum depression paradigm.

Cell therapy now constitutes an important area of regenerative medicine. The aging of the population has mandated the discovery and development of new and innovative therapeutic modalities to combat devastating disorders such as stroke. Menstrual blood and Sertoli cells represent two sources of viable transplantable cells that are gender-specific, both of which appear to have potential as donor cells for transplantation in stroke. During the subacute phase of stroke, the use of autologous cells offers effective and practical clinical application and is suggestive of the many benefits of using the aforementioned gender-specific cells. For example, in addition to being exceptionally immunosuppressive, testis-derived Sertoli cells secrete many growth and trophic factors and have been shown to aid in the functional recovery of animals transplanted with fetal dopaminergic cells. Correspondingly, menstrual blood cells are easily obtainable and exhibit angiogenic characteristics, proliferative capability, and pluripotency. Of further interest is the ability of menstrual blood cells, following transplantation in stroke models, to migrate to the infarct site, secrete neurotrophic factors, regulate the inflammatory response, and be steered towards neural differentiation. From cell isolation to transplantation, we emphasize in this review paper the practicality and relevance of the experimental and clinical use of gender-specific stem cells, such as Sertoli cells and menstrual blood cells, in the treatment of stroke.

Multiple sclerosis (MS) is characterized by widespread immunomodulatory demyelination of the central nervous system (CNS), resulting in nerve cell dysfunction. Accordingly, treatment strategies have been centered on immunodulation and remyelination, with the former primarily focused on reducing the pathology rather than enhancing myelin repair, which the latter targets. While conceding to the emerging view of heterogeneity in the pathology of MS, which precludes variations in degree of immune response (i.e., inflammation) and demyelination, the concept of enhancing myelin repair is appealing since it is likely to provide both disease-reducing and disease-inhibiting therapeutic approaches to MS. In this regard, we and several others have proposed that cell replacement therapy is an effective strategy to repair the myelin in MS. Here we hypothesize that transplantation of mouse bone marrow-derived oligodendrocytes (BMDOs) and BMDOs transfected with ephrin proteins (BMDO + ephrin), which are known to enhance cell and axonal migratory capacity, may produce therapeutic benefits in animal models of MS.

With a constellation of stem cell sources available, researchers hope to utilize their potential for cellular repair as a therapeutic target for disease. However, many lab-to-clinic translational considerations must be given in determining their efficacy, variables such as the host response, effects on native tissue, and potential for generating tumors. This review will discuss the current knowledge of stem cell research in neurological disease, mainly stroke, with a focus on the benefits, limitations, and clinical potential.

In pursuit of neurological therapies, the opioid system, specifically delta opioid receptors and delta opioid peptides, demonstrates promising therapeutic potential for stroke, Parkinson's disease, and other degenerative neurological conditions. Recent studies offer strong evidence in support of the therapeutic use of delta opioid receptors, and provide insights into the underlying mechanisms of action. Delta opioid receptors have been shown to confer protective effects by mediating ionic homeostasis and activating endogenous neuroprotective pathways. Additionally, delta opioid agonists such as (D-Ala 2, D-Leu 5) enkephalin (DADLE) have been shown to decrease apoptosis and promote neuronal survival. In its entirety, the delta opioid system represents a promising target for neural therapies.

Cell therapy is a major discipline of regenerative medicine that has been continually growing over the last two decades. The aging of the population necessitates discovery of therapeutic innovations to combat debilitating disorders, such as stroke. Menstrual blood and Sertoli cells are two gender-specific sources of viable transplantable cells for stroke therapy. The use of autologous cells for the subacute phase of stroke offers practical clinical application. Menstrual blood cells are readily available, display proliferative capacity, pluripotency and angiogenic features, and, following transplantation in stroke models, have the ability to migrate to the infarct site, regulate the inflammatory response, secrete neurotrophic factors, and have the possibility to differentiate into neural lineage. Similarly, the testis-derived Sertoli cells secrete many growth and trophic factors, are highly immunosuppressive, and exert neuroprotective effects in animal models of neurological disorders. We highlight the practicality of experimental and clinical application of menstrual blood cells and Sertoli cells to treat stroke, from cell isolation and cryopreservation to administration.

Stem cell therapy for adult stroke has reached limited clinical trials. Here, the authors provide translational research guidance on stem cell therapy for neonatal hypoxic–ischemic brain injury requiring a careful consideration of clinically relevant animal models, feasible stem cell sources and validated safety and efficacy end point assays, as well as a general understanding of modes of action of this cellular therapy. To this end, the authors refer to existing translational guidelines, in particular the recommendations outlined in the consortium of academicians, industry partners and regulators called Stem Cell Therapies as an Emerging Paradigm for Stroke. Although the Stem Cell Therapies as an Emerging Paradigm for Stroke guidelines are directed at enhancing the successful outcome of cell therapy in adult stroke, the authors highlight overlapping pathologies between adult stroke and neonatal hypoxic–ischemic brain injury. The authors are, however, cognizant that the neonatal hypoxic–ischemic brain injury displays disease symptoms distinct from adult stroke in need of an innovative translational approach that facilitates the entry of cell therapy in the clinic. Finally, insights into combination therapy are provided with the vision that stem cell therapy may benefit from available treatments, such as hypothermia, already being tested in children diagnosed with hypoxic–ischemic brain injury.

Mesenchymal stromal cells (MSCs) have been always considered as a useful option for therapeutic purposes. MSCs can be derived from many sources, perhaps one of the most therapeutically valuable sources is the Wharton’s Jelly (WJ), a gelatinous tissue layer found within the umbilical cord that contains myofibroblast-like stromal cells. Previous studies investigating Wharton’s Jelly-derived MSCs reveal that they have more powerful proliferative, immunosuppressive and therapeutic activities compared to MSCs derived from adult bone marrow or adipose tissue. The present review discusses the phenotypic features, potential therapeutic uses and optimization of experimental protocols for WJ-derived stem cells. Previous work show successful results when WJ-MSCs were used as transplantable cells for treatment of various diseases (e.g., cancer, chronic liver disease, cardiovascular diseases, nerve, cartilage, tendon injury and degenerated intervertebral disc). These positive results are attributed to favorable transplantable features the WJ-MSCs display which include ease of sourcing, in vitro expandability, differentiation abilities, immune-evasion and immune-regulation capacities. However, further research work is demanded to harness the benefits of WJ-MSCs into clinical application.

Summary Aims Traumatic brain injury (TBI) occurs when the head is impacted by an external force causing either a closed or penetrating head injury through a direct or accelerating impact. In laboratory research, most of the TBI animal models focus on a specific region to cause brain injury, but traumatic injuries in patients do not always impact the same brain regions. The aim of this study was to examine the histopathological effects of different angles of mechanical injury by manipulating the trajectory of the controlled cortical impact injury (CCI) model in adult Sprague‐Dawley rats. Methods The CCI model was manipulated as follows: conventional targeting of the frontal cortex, farthest right angle targeting the frontal cortex, closest right angle targeting the frontal cortex, olfactory bulb injury, and cerebellar injury. Three days after TBI, brains were harvested to analyze cortical and hippocampal cell loss, neuroinflammatory response, and neurogenesis via immunohistochemistry. Results Results revealed cell death in the M1 region of the cortex across all groups, and in the CA3 area from olfactory bulb injury group. This observed cell death involved upregulation of inflammation as evidenced by rampant MHCII overexpression in cortex, but largely spared Ki‐67/nestin neurogenesis in the hippocampus during this acute phase of TBI. Conclusion These results indicate a trajectory‐dependent injury characterized by exacerbation of inflammation and different levels of impaired cell proliferation and neurogenesis. Such multiple brain areas showing varying levels of cell death after region‐specific CCI model may closely mimic the clinical manifestations of TBI.

In pursuit of neurological therapies, the opioid system, specifically delta opioids and delta opioid peptides, demonstrates promising potential for stroke, Parkinson’s Disease, and other degenerative neurological conditions. Recent studies present strong evidence in support of the therapeutic use of delta opioid receptors, and provide insight into the underlying mechanisms of action. Delta opioid receptors have been shown to confer protective effects by mediating ionic homeostasis and activating endogenous neuroprotective pathways. Additionally, delta opioid agonists such as (D-Ala 2, D-Leu 5) enkephalin (DADLE) have been shown to decrease apoptosis and promote neuronal survival. In its entirety, the delta opioid system represents a promising target for neural therapies.

The Wharton’s jelly (WJ) of the umbilical cord has been identified as a rich source of mesenchymal stromal cells (MSCs), which are considered as promising candidates for stem cell-based therapy to treat several diseases. In particular, MSCs harvested from the “young” WJ are believed to be more proliferative, immunosuppressive and therapeutically active stem cells than those derived from adult tissues, such as the bone marrow or adipose. MSCs derived from WJ also exhibit transplantable features such as ease of sourcing, in vitro expandability, differentiation capacities, immune-evasion and immune-regulation profiles. Indeed, the potentiality of WJ-derived stem cells to treat cancer, cardiovascular and liver diseases, and nerve and cartilage tendon injuries has been suggested. In this paper, we present an overview of the phenotypic characteristics, immune-modulatory properties and therapeutic potentials of WJ-derived stem cells, and suggest optimization protocols for successful advancement of WJ-derived stem cells into clinical use.

Treatments for neonatal hypoxic-ischemic encephalopathy (HIE) have been limited. The aim of this paper is to offer translational research guidance on stem cell therapy for neonatal HIE by examining clinically relevant animal models, practical stem cell sources, safety and efficacy of endpoint assays, as well as a general understanding of modes of action of this cellular therapy. In order to do so, we discuss the clinical manifestations of HIE, highlighting its overlapping pathologies with stroke and providing insights on the potential of cell therapy currently investigated in stroke, for HIE. To this end, we draw guidance from recommendations outlined in stem cell therapeutics as an emerging paradigm for stroke or STEPS, which have been recently modified to Baby STEPS to cater for the "neonatal" symptoms of HIE. These guidelines recognized that neonatal HIE exhibit distinct disease symptoms from adult stroke in need of an innovative translational approach that facilitates the entry of cell therapy in the clinic. Finally, new information about recent clinical trials and insights into combination therapy are provided with the vision that stem cell therapy may benefit from available treatments, such as hypothermia, already being tested in children diagnosed with HIE.

Stroke is the third most common cause of death and severe disability among Western populations. Overall, the incidence of stroke is uniformly higher in men than in women. Stroke is rare in women during the reproductive years and rapidly increases after menopause, strongly suggesting that estrogen (E2) plays an important role in the prevention of stroke. Ongoing studies are currently evaluating both the benefits and the risks associated with E2 replacement therapy and hormone replacement therapy in stroke. Equally important is the role of E2 receptor (ER), as studies indicate that ER populations in several tissue sites may significantly change during stress and aging. Such changes may affect the patient's susceptibility to neurological disorders including stroke and greatly affect the response to selective E2 receptor modulators (SERMs). Replacement therapies may be inefficient with low ER levels. The goal of this review paper is to discuss an animal model that will allow investigations of the potential therapeutic effects of E2 and its derivatives in stroke. We hypothesize that E2 neuroprotection is, in part, receptor mediated. This hypothesis is a proof-of-principle approach to demonstrate a role for specific ER subtypes in E2 neuroprotection. To accomplish this, we use a retroviral-mediated gene transfer strategy that expresses subtypes of the ER gene in regions of the rat brain most susceptible to neuronal damage, namely, the striatum and the cortex. The animal model is exposed to experimental stroke conditions involving middle cerebral artery occlusion (MCAo) method, and eventually the extent of neuronal damage will be evaluated. A reduction in neuronal damage is expected when E2 is administered with specific ER subtypes. From this animal model, an optimal E2 dose and treatment regimen can be determined. The animal model can help identify potential E2-like therapeutics in stroke and screen for beneficial or toxic additives present in commercial E2 preparations that are currently available. Such studies will be informative in designing drug therapies for stroke.

Modified mesenchymal stromal cells (MSCs) display a unique mechanism of action during the repair phase of traumatic brain injury by exhibiting the ability to build a biobridge between the neurogenic niche and the site of injury. Immunohistochemistry and laser capture assay have visualized this biobridge in the area between the neurogenic subventricular zone and the injured cortex. This biobridge expresses high levels of extracellular matrix metalloproteinases (MMPs), which are initially co-localized with a stream of transplanted MSCs, but later this region contains only few to non-detectable grafts and becomes overgrown by newly recruited host cells. We have reported that long-distance migration of host cells from the neurogenic niche to the injured brain site can be attained via these transplanted stem cell-paved biobridges, which serve as a key regenerative process for the initiation of endogenous repair mechanisms. Thus, far the two major schools of discipline in stem cell repair mechanisms support the idea of "cell replacement" and the bystander effects of "trophic factor secretion." Our novel observation of stem cell-paved biobridges as pathways for directed migration of host cells from neurogenic niche toward the injured brain site adds another mode of action underlying stem cell therapy. More in-depth investigations on graft-host interaction will likely aid translational research focused on advancing this stem cell-paved biobridge from its current place, as an equally potent repair mechanism as cell replacement and trophic factor secretion, into a new treatment strategy for traumatic brain injury and other neurological disorders.

Traumatic brain injury (TBI) survivors exhibit motor and cognitive symptoms from the primary injury that can become aggravated over time because of secondary cell death. In the presentin vivostudy, we examined the beneficial effects of human adipose-derived stem cells (hADSCs) in a controlled cortical impact model of mild TBI using young (6 months) and aged (20 months) F344 rats. Animals were transplanted intravenously with 4 × 106hADSCs (Tx), conditioned media (CM), or vehicle (unconditioned media) at 3 h after TBI. Significant amelioration of motor and cognitive functions was revealed in young, but not aged, Tx and CM groups. Fluorescent imagingin vivoandex vivorevealed 1,1′ dioactadecyl-3-3-3′,3′-tetramethylindotricarbocyanine iodide-labeled hADSCs in peripheral organs and brain after TBI. Spatiotemporal deposition of hADSCs differed between young and aged rats, most notably reduced migration to the aged spleen. Significant reduction in cortical damage and hippocampal cell loss was observed in both Tx and CM groups in young rats, whereas less neuroprotection was detected in the aged rats and mainly in the Tx group but not the CM group. CM harvested from hADSCs with silencing of either NEAT1 (nuclear enriched abundant transcript 1) or MALAT1 (metastasis associated lung adenocarcinoma transcript 1), long noncoding RNAs (lncRNAs) known to play a role in gene expression, lost the efficacy in our model. Altogether, hADSCs are promising therapeutic cells for TBI, and lncRNAs in the secretome is an important mechanism of cell therapy. Furthermore, hADSCs showed reduced efficacy in aged rats, which may in part result from decreased homing of the cells to the spleen.

Cells of the central nervous system were once thought to be incapable of regeneration. This brain repair limitation makes neurological disorders particularly devastating as the associated degeneration was thought to be irreversible. However, recent advances in the understanding of stem cells and endogenous repair systems of the central nervous system have led to the development of potential neuroregenerative therapies. Pluripotent embryonic stem cells have shown promise in alleviating deficits associated with Parkinson’s disease and cerebral ischemia. However, their substantial capacity for proliferation also puts them at a high risk of becoming tumorigenic. Multipotent adult stem cells, such as mesenchymal stem cells derived from adult bone marrow, are more limited in their differentiating capacity, but do not possess the same risk of teratoma formation as embryonic and fetal stem cells. While embryonic and adult stem cell therapies commonly focus on cell replacement, recent studies are also evaluating the efficacy of using stem cells to stimulate endogenous neuroprotective mechanisms via secretion of therapeutic molecules. While substantial progress in the use of stem cells has been made, potential cell-based therapies remain hindered by numerous optimization challenges associated with translation of the cell transplant regimen from the laboratory to the clinic. In order to optimize stem cell therapy, translational factors such as cell dosage, route of administration, type of transplant (autologous or allogenic), and the use of immunosuppression require critical assessment of safety and efficacy for clinical applications.

With limited clinical trials on stem cell therapy for adult stroke underway, the assessment of efficacy also needs to be considered for neonatal hypoxic-ischemic brain injury, considering its distinct symptoms. The critical nature of this condition leads to establishment of deficits that last a lifetime. Here, we will highlight the progress of current translational research, commenting on the critical nature of the disease, stem cell sources, the use of hypothermia, safety and efficacy of each treatment, modes of action, and the possibility of combination therapy. With this in mind, we reference translational guidelines established by a consortium of research partners called Stem cell Therapeutics as an Emerging Paradigm for Stroke (STEPS). The guidelines of STEPS are directed toward evaluating outcomes of cell therapy in adult stroke; however, we identify the overlapping pathology, as we believe that these guidelines will serve well in the investigation of neonatal hypoxic-ischemic therapy. Finally, we discuss emerging treatments and a case report, altogether suggesting that the potential for these treatments to be used in synergy has arrived and the time for advancing stem cell use in combination with hypothermia for cerebral palsy is now.

Stem cells exert therapeutic effects for central nervous system (CNS) trauma. Accumulating evidence reveals that stem cell-based therapies for CNS trauma can be achieved via transplantation of exogenous stem cells or stimulation of endogenous stem cells from the neurogenic niches of subventricular zone and subgranular zone, or recruited from the bone marrow through peripheral circulation. In this chapter, we review the different sources of stem cells that have been tested in animal models of CNS trauma, highlighting the research progress on stem cell-based therapeutics in stroke and their extension to traumatic brain injury (TBI). In addition, we discuss specific mechanisms of action, in particular neurovascular repair by endothelial progenitor cells, as key translational research for advancing the clinical applications of stem cells for CNS trauma.

Histone deacetylases (HDACs), originally described as histone modifiers, have more recently been demonstrated to modify a variety of other proteins involved in diverse cellular processes unrelated to the chromatin environment, including the modulation of proteins related to cell cycle/apoptosis and immune regulation. In contrast to the well-documented effects of HDAC inhibitors (HDACi) in the control of cell cycle and apoptosis, their role in immunobiology is still not completely understood, and the reported immunological outcomes when using HDACi are heterogeneous. Our group recently reported that the pharmacological or genetic abrogation of a single HDAC, HDAC6, modulates the expression of immuno-regulatory proteins, including PD-L1, PD-L2, MHC class I, B7-H4 and TRAIL-R1. We primarily focused in PD-L1, which is an important negative regulator of T-cell function and often over-expressed in cancer cells. In a mechanistic point of view, we have found that the pharmacological inhibition and genetic abrogation of HDAC6 inactivates the STAT3 pathway, impairs the nuclear translocation and the recruitment of STAT3 to the PD-L1 promoter and subsequently down-regulates the expression of PD-L1. Moreover, the in vivo abrogation of HDAC6 reduces tumor growth in melanoma models, effect that is enhanced in the presence of the immune check-point blocking antibodies anti-PD-1 and anti-CTLA4. These results provide a key pre-clinical rationale and justification to further study isotype selective HDAC6 inhibitors as potential immunomodulatory agents in cancer. Citation Format: Tessa Knox, Maritza Lienlaf, Patricio Perez, Mibel Pabon, Calvin Lee, Fengdong Cheng, Eva Sahakian, John Powers, Susan Deng, Smalley Keiran, Alan Kozikowski, Javier Pinilla, Amod Sarnaik, Ed Seto, Jeffrey Weber, Eduardo Sotomayor, Alejandro Villagra. HDAC6, new role as master regulator of PD-L1 and immune-related pathways. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2331.

Background Comprehensive stroke studies reveal diaschisis, a loss of function due to pathological deficits in brain areas remote from initial ischemic lesion. However, blood-brain barrier (BBB) competence in subacute diaschisis is uncertain. The present study investigated subacute diaschisis in a focal ischemic stroke rat model. Specific focuses were BBB integrity and related pathogenic processes in contralateral brain areas. Methodology/Principal Findings In ipsilateral hemisphere 7 days after transient middle cerebral artery occlusion (tMCAO), significant BBB alterations characterized by large Evans Blue (EB) parenchymal extravasation, autophagosome accumulation, increased reactive astrocytes and activated microglia, demyelinization, and neuronal damage were detected in the striatum, motor and somatosensory cortices. Vascular damage identified by ultrastuctural and immunohistochemical analyses also occurred in the contralateral hemisphere. In contralateral striatum and motor cortex, major ultrastructural BBB changes included: swollen and vacuolated endothelial cells containing numerous autophagosomes, pericyte degeneration, and perivascular edema. Additionally, prominent EB extravasation, increased endothelial autophagosome formation, rampant astrogliosis, activated microglia, widespread neuronal pyknosis and decreased myelin were observed in contralateral striatum, and motor and somatosensory cortices. Conclusions/Significance These results demonstrate focal ischemic stroke-induced pathological disturbances in ipsilateral, as well as in contralateral brain areas, which were shown to be closely associated with BBB breakdown in remote brain microvessels and endothelial autophagosome accumulation. This microvascular damage in subacute phase likely revealed ischemic diaschisis and should be considered in development of treatment strategies for stroke.

Stem cells exert therapeutic effects against ischemic stroke via transplantation of exogenous stem cells or stimulation of endogenous stem cells within the neurogenic niches of subventricular zone and subgranular zone, or recruited from the bone marrow through peripheral circulation. In this paper, we review the different sources of stem cells that have been tested in animal models of stroke. In addition, we discuss specific mechanisms of action, in particular neurovascular repair by endothelial progenitor cells, as key translational research for advancing the clinical applications of stem cells for ischemic stroke.

Background: Parkinson’s disease is characterized by a progressive loss of dopaminergic neurons in the substantia nigra. The cause of the neurodegeneration is unknown. Neuroinflammation has been clearly shown in Parkinson’s disease and may be involved in the progressive nature of the disease. Microglia are capable of producing neuronal damage through the production of bioactive molecules such as cytokines, as well as reactive oxygen species (ROS), and nitric oxide (NO). The inflammatory response in the brain is tightly regulated at multiple levels. One form of immune regulation occurs via neurons. Fractalkine (CX3CL1), produced by neurons, suppresses the activation of microglia. CX3CL1 is constitutively expressed. It is not known if addition of exogenous CX3CL1 beyond otherwise physiologically normal levels could decrease microglia activation and thereby minimize the secondary neurodegeration following a neurotoxic insult. Methods: The intrastriatal 6-hydroxydopamine (6-OHDA) rat model of Parkinson disease, was used to test the hypothesis that exogenous CX3CL1 could be neuroprotective. Treatment with recombinant CX3CL1 was delivered to the striatum by an osmotic minipump for 28 days beginning 7 days after the initial insult. Unbiased stereological methods were used to quantify the lesion size in the striatum, the amount of neuronal loss in the substantia nigra, and the amount of microglia activation. Results: As hypothesized, CX3CL1 was able to suppress this microglia activation. The reduced microglia activation was found to be neuroprotective as the CX3CL1 treated rats had a smaller lesion volume in the striatum and importantly significantly fewer neurons were lost in the CX3CL1 treated rats. Conclusion: These findings demonstrated that CX3CL1 plays a neuroprotective role in 6-OHDA-induced dopaminergic lesion and it might be an effective therapeutic target for many neurodegenerative diseases, including Parkinson disease and Alzheimer disease, where inflammation plays an important role. Background Parkinson’s disease (PD) is a neurodegenerative disorder affecting the motor system including motor coordination and speed as well as producing rigidity and tremor. The symptoms of PD are mainly due to a progressive loss of dopaminergic neurons within the pars compacta of the substantia nigra (SNpc). This degeneration decreases the levels of the neurotransmitter dopamine in the nigrostriatal system. In the past 15 years, an increasing amount of evidence has emerged to suggest

Inflammation in the brain plays a major role in neurodegenerative diseases. In particular, microglial cell activation is believed to be associated with the pathogenesis of neurodegenerative diseases, including Parkinson's disease (PD). An increase in microglia activation has been shown in the substantia nigra pars compacta (SNpc) of PD models when there has been a decrease in tyrosine hydroxylase (TH) positive cells. This may be a sign of neurotoxicity due to prolonged activation of microglia in both early and late stages of disease progression. Natural products, such as spirulina, derived from blue green algae, are believed to help reverse this effect due to its anti-inflammatory/anti-oxidant properties. An adeno-associated virus vector (AAV9) for α-synuclein was injected in the substantia nigra of rats to model Parkinson's disease and to study the effects of spirulina on the inflammatory response. One month prior to surgeries, rats were fed either a diet enhanced with spirulina or a control diet. Immunohistochemistry was analyzed with unbiased stereological methods to quantify lesion size and microglial activation. As hypothesized, spirulina was neuroprotective in this α-synuclein model of PD as more TH+ and NeuN+ cells were observed; spirulina concomitantly decreased the numbers of activated microglial cells as determined by MHCII expression. This decrease in microglia activation may have been due, in part, to the effect of spirulina to increase expression of the fractalkine receptor (CX3CR1) on microglia. With this study we hypothesize that α-synuclein neurotoxicity is mediated, at least in part, via an interaction with microglia. We observed a decrease in activated microglia in the rats that received a spirulina- enhanced diet concomitant to neuroprotection. The increase in CX3CR1 in the groups that received spirulina, suggests a potential mechanism of action.

Background Neurogenesis continues to occur throughout life but dramatically decreases with increasing age. This decrease is mostly related to a decline in proliferative activity as a result of an impoverishment of the microenvironment of the aged brain, including a reduction in trophic factors and increased inflammation. Results We determined that human umbilical cord blood mononuclear cells (UCBMC) given peripherally, by an intravenous injection, could rejuvenate the proliferative activity of the aged neural stem/progenitor cells. This increase in proliferation lasted for at least 15 days after the delivery of the UCBMC. Along with the increase in proliferation following UCBMC treatment, an increase in neurogenesis was also found in the aged animals. The increase in neurogenesis as a result of UCBMC treatment seemed to be due to a decrease in inflammation, as a decrease in the number of activated microglia was found and this decrease correlated with the increase in neurogenesis. Conclusion The results demonstrate that a single intravenous injection of UCBMC in aged rats can significantly improve the microenvironment of the aged hippocampus and rejuvenate the aged neural stem/progenitor cells. Our results raise the possibility of a peripherally administered cell therapy as an effective approach to improve the microenvironment of the aged brain.

INTRODUCTION: In the microenvironment of CLL, T cells are characteristically dysfunctional compared to a normal, healthy setting. Idelalisib, an approved PI3Kδ inhibitor has shown successful clinical response in relapsed/refractory CLL, but is associated with a high rate of discontinuation because of likely immune-related severe adverse events (SAE). More recently, increased toxicity has been reported in treatment-naïve patient trials. The described hepatotoxicity, colitis, and pneumonitis appear to be associated with changes in the T cell compartment and specifically regulatory T cells (Tregs). In the phase I trials of the next generation PI3Kδ inhibitor, TGR-1202, a comparable rate of clinical responses have been reported with apparently less toxicity than prior PI3Kδ inhibitors, even with long term follow-up (Burris et al, ASCO 2016). We previously demonstrated in vitrothat TGR-1202 relatively preserved the number and function of normal human T cell subsets, including Tregs, when compared to the other clinically available PI3Kδ inhibitors (Maharaj et al AACR 2016) Herein, we aimed to further investigate how TGR-1202 regulates T cell subsets in a preclinical murine model of CLL. METHODS: For the preclinical model of CLL, we adoptively transferred 25x10^6 leukemic euTCL1 splenocytes into wildtype mice. Following establishment of disease, we orally administered TGR-1202 or duvelisib (PI3Kδγ inhibitor) and quantified immune changes over time using flow cytometry to detect T cell subsets and associated functional markers. Duvelisb was chosen as a comparator since idelalisib is not suitable for murine models, and duvelisib has been shown to have similar efficacy and toxicity as idelalisib in preclinical and clinical studies. RESULTS: First, we confirmed general immune changes typical of CLL progression. Peripheral white blood cell (WBC) count was significantly higher in leukemic mice compared to wildtype (p=0.02). Following oral TGR-1202 or duvelisib treatment, WBC count decreased significantly over time (p CONCLUSIONS: In conclusion, we have demonstrated the efficacy of two PI3Kδinhibitors in a murine CLL model and their differential impact on Treg and Th17 compartments, which may be of relevance to study the toxicity in this class of drugs. Extensive studies of the immune modulating effects of TGR-1202 are particularly of interest given its current clinical development and considering the lower rate of SAE observed in trials. Disclosures Miskin: TG Therapeutics, Inc: Employment, Equity Ownership. Maryanski:TG Therapeutics, Inc.: Employment, Equity Ownership. Pinilla-Ibarz:Janssen: Consultancy, Honoraria; Pharmacyclics: Consultancy, Speakers Bureau; Novartis: Consultancy; Gilead: Consultancy, Speakers Bureau; Abbvie: Consultancy, Speakers Bureau.

Ibrutinib, a Bruton tyrosine kinase (BTK) inhibitor is now FDA approved for front line and relapsed and refractory CLL. Although this drug has been shown to be successful in controlling the disease, most patients only reach partial responses (PR) likely secondary to activation of alternative and redundant BCR signaling pathways. In the past several years, epigenetic changes in CLL have gained special attention (Tong et al 2010) because of their intricate interplay with previously described genetic events and its active role in the regulation of pathogenesis and immune-related pathways (Stilgenbauer et al 2002). Recent publications have described the differential expression of specific HDACs in CLL, as well as the impact of global histone deacetylase activity and its relation with progression and overall survival (Van Damme et al 2014, Yang et al 2015). Previously, we had reported that expression of HDAC6 is increased in CLL patient samples and cell lines. We have also demonstrated that modulation of this HDAC, effects cell proliferation and viability in CLL cell lines. Additionally, treatment with HDAC6i (ACY-738 - a potent and selective HDAC6i) demonstrated increased overall survival in euTCL1 mice, a murine CLL model. Treatment of euTCL1 mice (both adoptive transfer and aging model) with ACY-738 as a single agent resulted in 1) overall survival advantage, 2) reduction of tumor burden, 3) reduction in PD-L1 expression in the malignant B cell population and 4) decreased circulating Treg numbers. Furthermore, we demonstrated that in an in vitrostudy, treatment of HDAC6i with ibrutinib in CLL cell lines render strong synergistic cell killing. In our current study of this combinatorial approach, using the adoptive transfer euTCL1 model receiving Ibrutinib in drinking water and ACY-738 in feed, we demonstrate a further decrease in tumor burden when compared to single agent treatment with either compound alone. This observed effect on tumor burden occurred in conjunction with decreases in co-inhibitory molecules and circulating Treg frequency. The combination was well tolerated and no significant toxicity was observed. Since aberrant over-expression of HDAC6 in CLL cell lines and patient's samples have already been demonstrated (Van Damme et al 2012, Sahakian et al 2012) we sought to understand its mechanistic role in BCR survival pathways of CLL. Our studiesin normal B cells isolated from C57BL/6 and HDAC6KO mice, demonstrated a reduction in phosphorylation of BTK, ERK, and AKT. Similar results were observed when we compared euTCL1 to euTCL1/HDAC6KO B cells. Additionally,we observed decreased phosphorylation of ERK and SYK in MEC2-HDAC6KD cells when compared to parental control CLL cells. Moreover, RNA-Seq studies of the eu-TCL1/HDAC6KO versus euTCL1 B cells showed several key BCR signaling proteins altered by the deletion of HDAC6. In conclusion, these results from our preclinical CLL models suggest that combinatorial therapy of Ibrutinib plus HDAC6i show synergistic inhibition of BCR signaling and therefore a better overall treatment outcome. Disclosures Quayle: Acetylon Pharmaceuticals: Employment, Equity Ownership. Jones:Acetylon Pharmaceuticals, Inc.: Employment, Equity Ownership. Pinilla-Ibarz:Gilead: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy, Speakers Bureau; Novartis: Consultancy; Abbvie: Consultancy, Speakers Bureau; Novartis: Consultancy; Janssen: Consultancy, Honoraria; Gilead: Consultancy, Speakers Bureau.