Electrical modulation of transplanted stem cells improves functional recovery in a rodent model of stroke.

Stroke is a leading cause of long-term disability worldwide, intensifying the need for effective recovery therapies. Stem cells are a promising stroke therapeutic, but creating ideal conditions for treatment is essential. Here we developed a conductive polymer system for stem cell delivery and electrical modulation in animals. Using this system, electrical modulation of human stem cell transplants improve functional stroke recovery in rodents. Increased endogenous stem cell production corresponds with improved function. Transcriptome analysis identified stanniocalcin 2 (STC2) as one of the genes most significantly upregulated by electrical stimulation. Lentiviral upregulation and downregulation of STC2 in the transplanted stem cells demonstrate that this glycoprotein is an essential mediator in the functional improvements seen with electrical modulation. Moreover, intraventricular administration of recombinant STC2 post-stroke confers functional benefits. In summation, our conductive polymer system enables electrical modulation of stem cells as a potential method to improve recovery and identify important therapeutic targets.

Electrical stimulation of human neural stem cells via conductive polymer nerve guides enhances peripheral nerve recovery.

Severe peripheral nerve injuries often result in permanent loss of function of the affected limb. Current treatments are limited by their efficacy in supporting nerve regeneration and behavioral recovery. Here we demonstrate that electrical stimulation through conductive nerve guides (CNGs) enhances the efficacy of human neural progenitor cells (hNPCs) in treating a sciatic nerve transection in rats. Electrical stimulation strengthened the therapeutic potential of NPCs by upregulating gene expression of neurotrophic factors which are critical in augmenting synaptic remodeling, nerve regeneration, and myelination. Electrically-stimulated hNPC-containing CNGs are significantly more effective in improving sensory and motor functions starting at 1-2 weeks after treatment than either treatment alone. Electrophysiology and muscle assessment demonstrated successful re-innervation of the affected target muscles in this group. Furthermore, histological analysis highlighted an increased number of regenerated nerve fibers with thicker myelination in electrically-stimulated hNPC-containing CNGs. The elevated expression of tyrosine kinase receptors (Trk) receptors, known to bind to neurotrophic factors, indicated the long-lasting effect from electrical stimulation on nerve regeneration and distal nerve re-innervation. These data suggest that electrically-enhanced stem cell-based therapy provides a regenerative rehabilitative approach to promote peripheral nerve regeneration and functional recovery.

Engineered stem cell mimics to enhance stroke recovery.

Currently, no medical therapies exist to augment stroke recovery. Stem cells are an intriguing treatment option being evaluated, but cell-based therapies have several challenges including developing a stable cell product with long term reproducibility. Since much of the improvement observed from cellular therapeutics is believed to result from trophic factors the stem cells release over time, biomaterials are well-positioned to deliver these important molecules in a similar fashion. Here we show that essential trophic factors secreted from stem cells can be effectively released from a multi-component hydrogel system into the post-stroke environment. Using our polymeric system to deliver VEGF-A and MMP-9, we improved recovery after stroke to an equivalent degree as observed with traditional stem cell treatment in a rodent model. While VEGF-A and MMP-9 have many unique mechanisms of action, connective tissue growth factor (CTGF) interacts with both VEGF-A and MMP-9. With our hydrogel system as well as with stem cell delivery, the CTGF pathway is shown to be downregulated with improved stroke recovery.

Electrically Conductive Scaffold to Modulate and Deliver Stem Cells.

Stem cell therapy has emerged as an exciting stroke therapeutic, but the optimal delivery method remains unclear. While the technique of microinjection has been used for decades to deliver stem cells in stroke models, this technique is limited by the lack of ability to manipulate the stem cells prior to injection. This paper details a method of using an electrically conductive polymer scaffold for stem cell delivery. Electrical stimulation of stem cells using a conductive polymer scaffold alters the stem cell's genes involved in cell survival, inflammatory response, and synaptic remodeling. After electrical preconditioning, the stem cells on the scaffold are transplanted intracranially in a distal middle cerebral artery occlusion rat model. This protocol describes a powerful technique to manipulate stem cells via a conductive polymer scaffold and creates a new tool to further develop stem cell-based therapy.

Vitamin D Status and Cardiovascular Risk in Obesity: Effect of Physical Activity in Nonvitamin D Supplemented Adolescents.

BACKGROUND: The relationship among inadequate vitamin D status, obesity, and cardiometabolic risk and the potential impact of physical activity-based interventions on vitamin D status are poorly characterized in children. This study aimed to address these issues. METHODS: We studied a total of 21 adolescents (15 obese and 6 normal weight; age: 14-18 years; Tanner stage>IV). Adolescents with obesity (n = 15) underwent a randomized controlled (8 in the intervention group and 7 in the control group) 3-month physical activity-based lifestyle intervention. 25-Hydroxy vitamin D [25(OH)D] by mass spectrometry, adiponectin, leptin, high-sensitivity C-reactive protein (CRP), insulin, and glucose were measured and body composition was assessed by dual-energy x-ray absorptiometry (DXA). Analysis of covariance and mixed-effects model were used to compare mean change in 25(OH)D between intervention and nonintervention groups. Bootstrap method was used to validate the estimates and principle component analysis reduced the variables in the data for adjustment. RESULTS: 25(OH)D was lower (P < 0.001) in the obese versus lean adolescents. Homeostasis model assessment-insulin resistance, CRP, fat mass (FM), and body mass index z-score were negatively correlated with baseline 25(OH)D, while adiponectin showed a positive correlation. After adjustment for baseline biomarkers of cardiometabolic risk, the concentration of 25(OH)D increased in the obese intervention group (P = 0.06), but not in the nonintervention group. Fat-free mass increased and FM decreased (P < 0.05 for both) in the intervention group. The magnitudes of increase in 25(OH)D and decrease in FM directly correlated (P < 0.05). CONCLUSIONS: The increase in circulating 25(OH)D concentration by physical activity-based lifestyle-only intervention in adolescents with obesity, who did not receive vitamin D supplementation, suggests a putative independent role of physical activity-based interventions in the regulation of vitamin D status and potentially in the mitigation of risk factors of cardiovascular disease.

Electrical preconditioning of stem cells with a conductive polymer scaffold enhances stroke recovery.

Exogenous human neural progenitor cells (hNPCs) are promising stroke therapeutics, but optimal delivery conditions and exact recovery mechanisms remain elusive. To further elucidate repair processes and improve stroke outcomes, we developed an electrically conductive, polymer scaffold for hNPC delivery. Electrical stimulation of hNPCs alters their transcriptome including changes to the VEGF-A pathway and genes involved in cell survival, inflammatory response, and synaptic remodeling. In our experiments, exogenous hNPCs were electrically stimulated (electrically preconditioned) via the scaffold 1 day prior to implantation. After in vitro stimulation, hNPCs on the scaffold are transplanted intracranially in a distal middle cerebral artery occlusion rat model. Electrically preconditioned hNPCs improved functional outcomes compared to unstimulated hNPCs or hNPCs where VEGF-A was blocked during in vitro electrical preconditioning. The ability to manipulate hNPCs via a conductive scaffold creates a new approach to optimize stem cell-based therapy and determine which factors (such as VEGF-A) are essential for stroke recovery.