Preclinical and dose-ranging assessment of hESC-derived dopaminergic progenitors for a clinical trial on Parkinson's disease.

Human embryonic stem cell (hESC)-derived midbrain dopaminergic (mDA) cell transplantation is a promising therapeutic strategy for Parkinson's disease (PD). Here, we present the derivation of high-purity mDA progenitors from clinical-grade hESCs on a large scale under rigorous good manufacturing practice (GMP) conditions. We also assessed the toxicity, biodistribution, and tumorigenicity of these cells in immunodeficient rats in good laboratory practice (GLP)-compliant facilities. Various doses of mDA progenitors were transplanted into hemi-parkinsonian rats, and a significant dose-dependent behavioral improvement was observed with a minimal effective dose range of 5,000-10,000 mDA progenitor cells. These results provided insights into determining a low cell dosage (3.15 million cells) for human clinical trials. Based on these results, approval for a phase 1/2a clinical trial for PD cell therapy was obtained from the Ministry of Food and Drug Safety in Korea, and a clinical trial for treating patients with PD has commenced.

Trophoblast glycoprotein is a marker for efficient sorting of ventral mesencephalic dopaminergic precursors derived from human pluripotent stem cells.

Successful cell therapy for Parkinson's disease (PD) requires large numbers of homogeneous ventral mesencephalic dopaminergic (vmDA) precursors. Enrichment of vmDA precursors via cell sorting is required to ensure high safety and efficacy of the cell therapy. Here, using LMX1A-eGFP knock-in reporter human embryonic stem cells, we discovered a novel surface antigen, trophoblast glycoprotein (TPBG), which was preferentially expressed in vmDA precursors. TPBG-targeted cell sorting enriched FOXA2+LMX1A+ vmDA precursors and helped attain efficient behavioral recovery of rodent PD models with increased numbers of TH+, NURR1+, and PITX3+ vmDA neurons in the grafts. Additionally, fewer proliferating cells were detected in TPBG+ cell-derived grafts than in TPBG- cell-derived grafts. Our approach is an efficient way to obtain enriched bona fide vmDA precursors, which could open a new avenue for effective PD treatment.

Potential for Dependence on Lisdexamfetamine - In vivo and In vitro Aspects.

Although lisdexamfetamine is used as a recreational drug, little research exists regarding its potential for dependence or its precise mechanisms of action. This study aims to evaluate the psychoactivity and dependence profile of lisdexamfetamine using conditioned place preference and self-administration paradigms in rodents. Additionally, biochemical techniques are used to assess alterations in the dopamine levels in striatal synaptosomes following administration of lisdexamfetamine. Lisdexamfetamine increased both conditioned place preference and self-administration. Moreover, after administration of the lisdexamfetamine, dopamine levels in the striatal synaptosomes were significantly increased. Although some modifications should be made to the analytical methods, performing high performance liquid chromatography studies on synaptosomes can aid in predicting dependence liability when studying new psychoactive substances in the future. Collectively, lisdexamfetamine has potential for dependence possible via dopaminergic pathway.

5-(2-Aminopropyl)benzofuran and phenazepam demonstrate the possibility of dependence by increasing dopamine levels in the brain.

Although 5-(2-aminopropyl)benzofuran (5-APB) and 7-bromo-5-(2-chlorophenyl)-1,3-dihydro-2H-1,4-benzodiazepin-2-one (phenazepam) are being used as recreational drugs, research on their dependence liability or mechanisms of action is lacking. The present study aimed to evaluate the behavioral effects and dependence liability of these drugs using conditioned place preference and self-administration paradigms in rodents. Additionally, biochemical techniques were used to assess the substance-induced alterations in synaptosome-released dopamine. While both of the tested substances elicited increases in conditioned place preference and dopamine, neither of them facilitated self-administration, suggesting that 5-APB and phenazepam have rewarding effects, rather than reinforcing effects.

Enhanced recovery from chronic ischemic injury by bone marrow cells in a rat model of ischemic stroke.

Even after decades of intensive studies, therapeutic options for patients with stroke are rather limited. Thrombolytic drugs effectively treat the very acute stage of stroke, and several neuroprotectants that are designed to treat secondary injury following stroke are being tested in clinical trials. However, these pharmacological approaches primarily focus on acute stroke recovery, and few options are available for treating chronic stroke patients. In recent years, stem cell-mediated regenerative approaches have emerged as promising therapeutic strategies for treating the chronic stage of stroke. In this study, we examined whether systemically administered bone marrow cells (BMCs) could have beneficial effects in a rat model of chronic ischemia. Our transplantation experiments using BMCs obtained from ischemic donor rats showed functional and structural recovery during the chronic stage of stroke. BMC-mediated neural proliferation was prominent in the brains of rats with chronic stroke, and most of the new cells eventually became neurons instead of astrocytes. BMC-mediated enhanced neural proliferation coincided with a significant reduction (∼50%) in the number of activated microglia, which is consistent with previous reports of enhanced neural proliferation being linked to microglial inactivation. Strikingly, approximately 57% of the BMCs that infiltrated the chronic ischemic brain were CD25(+) cells, suggesting that these cells may exert the beneficial effects associated with BMC transplantation. Based on the reported anti-inflammatory role of CD25(+) regulatory T-cells in acute experimental stroke, we propose a working model delineating the positive effects of BMC transplantation during the chronic phase of stroke; infiltrating BMCs (mostly CD25(+) cells) reduce activated microglia, which leads to enhanced neural proliferation and enhanced recovery from neuronal damage in this rat model of chronic stroke. This study provides valuable insights into the effect of BMC transplantation in the chronic ischemic brain, which may lead to the development of effective therapy for chronic stroke patients who currently lack satisfactory therapeutic options.