Temporary induction of hypoxic adaptations by preconditioning fails to enhance Schwann cell transplant survival after spinal cord injury.

Hypoxic preconditioning is protective in multiple models of injury and disease, but whether it is beneficial for cells transplanted into sites of spinal cord injury (SCI) is largely unexplored. In this study, we analyzed whether hypoxia-related preconditioning protected Schwann cells (SCs) transplanted into the contused thoracic rat spinal cord. Hypoxic preconditioning was induced in SCs prior to transplantation by exposure to either low oxygen (1% O2 ) or pharmacological agents (deferoxamine or adaptaquin). All preconditioning approaches induced hypoxic adaptations, including increased expression of HIF-1α and its target genes. These adaptations, however, were transient and resolved within 24 h of transplantation. Pharmacological preconditioning attenuated spinal cord oxidative stress and enhanced transplant vascularization, but it did not improve either transplanted cell survival or recovery of sensory or motor function. Together, these experiments show that hypoxia-related preconditioning is ineffective at augmenting either cell survival or the functional outcomes of SC-SCI transplants. They also reveal that the benefits of hypoxia-related adaptations induced by preconditioning for cell transplant therapies are not universal.

Treatment with hypoxia-mimetics protects cultured rat Schwann cells against oxidative stress-induced cell death.

Schwann cell (SC) grafts promote axon regeneration in the injured spinal cord, but transplant efficacy is diminished by a high death rate in the first 2-3 days postimplantation. Both hypoxic preconditioning and pharmacological induction of the cellular hypoxic response can drive cellular adaptations and improve transplant survival in a number of disease/injury models. Hypoxia-inducible factor 1 alpha (HIF-1α), a regulator of the cellular response to hypoxia, is implicated in preconditioning-associated protection. HIF-1α cellular levels are regulated by the HIF-prolyl hydroxylases (HIF-PHDs). Pharmacological inhibition of the HIF-PHDs mimics hypoxic preconditioning and provides a method to induce adaptive hypoxic responses without direct exposure to hypoxia. In this study, we show that hypoxia-mimetics, deferoxamine (DFO) and adaptaquin (AQ), enhance HIF-1α stability and HIF-1α target gene expression. Expression profiling of hypoxia-related genes demonstrates that HIF-dependent and HIF-independent expression changes occur. Analyses of transcription factor binding sites identify several candidate transcriptional co-regulators that vary in SCs along with HIF-1α. Using an in vitro model system, we show that hypoxia-mimetics are potent blockers of oxidative stress-induced death in SCs. In contrast, traditional hypoxic preconditioning was not protective. The robust protection induced by pharmacological preconditioning, particularly with DFO, indicates that pharmacological induction of hypoxic adaptations could be useful for promoting transplanted SC survival. These agents may also be more broadly useful for protecting SCs, as oxidative stress is a major pathway that drives cellular damage in the context of neurological injury and disease, including demyelinating diseases and peripheral neuropathies.

Efficacy of a Novel Telehealth Application in Health Behavior Modification and Symptomology in Military Service Members at Risk for Post-traumatic Osteoarthritis.

INTRODUCTION: Mobile applications (apps) may be beneficial to promote self-management strategies to mitigate the risk of developing post-traumatic osteoarthritis in military members following a traumatic knee injury. This study investigated the efficacy of a mobile app in facilitating behavior modification to improve function and symptomology among military members. MATERIALS AND METHODS: This is a preliminary pre and post hoc analysis of a randomized control trial. The MARX scale, Intermittent and Constant Osteoarthritis Pain (ICOAP) questionnaire, and the Knee Injury and Osteoarthritic Outcome Score Readiness to Manage Osteoarthritis Questionnaire were completed at baseline, 6-week, 6-month, and 12-month follow-up. Participants in the treatment arm completed the System Usability Scale. Data were analyzed using descriptive statistics, the Wilcoxon sum of ranks test, the Wilcoxon signed-rank test, and Cohen's d effect size. RESULTS: A total of 28 participants were included. Between-group differences for baseline and 6-week follow-up were significantly improved in the injured knee ICOAP constant pain score for the treatment group (treatment: -4.2 ± 12, 95% CI: -11.5, 3.1; control: 5.5 ± 9.9, 95% CI: 0.9, 10.1; P = .035, effect size = 0.905). Within-group differences for baseline and 6-week follow-up demonstrated a significant decline in the injured knee ICOAP constant pain score among the control group (signed-rank: 16.0, P = .031, Cohen's d = 0.339). No other significant differences were observed. A good System Usability Scale score for usability was found (76.6 ± 8.8). CONCLUSIONS: These results indicate that the mobile app is easy to use and may contribute to improved constant pain symptomology for patients at risk for post-traumatic osteoarthritis.

Hypoxia-Inducible Factor 1α (HIF-1α) Counteracts the Acute Death of Cells Transplanted into the Injured Spinal Cord.

Cellular transplantation is in clinical testing for a number of central nervous system disorders, including spinal cord injury (SCI). One challenge is acute transplanted cell death. To prevent this death, there is a need to both establish when the death occurs and develop approaches to mitigate its effects. Here, using luciferase (luc) and green fluorescent protein (GFP) expressing Schwann cell (SC) transplants in the contused thoracic rat spinal cord 7 d postinjury, we establish via in vivo bioluminescent (IVIS) imaging and stereology that cell death occurs prior to 2-3 d postimplantation. We then test an alternative approach to the current paradigm of enhancing transplant survival by including multiple factors along with the cells. To stimulate multiple cellular adaptive pathways concurrently, we activate the hypoxia-inducible factor 1α (HIF-1α) transcriptional pathway. Retroviral expression of VP16-HIF-1α in SCs increased HIF-α by 5.9-fold and its target genes implicated in oxygen transport and delivery (VEGF, 2.2-fold) and cellular metabolism (enolase, 1.7-fold). In cell death assays in vitro, HIF-1α protected cells from H2O2-induced oxidative damage. It also provided some protection against camptothecin-induced DNA damage, but not thapsigargin-induced endoplasmic reticulum stress or tunicamycin-induced unfolded protein response. Following transplantation, VP16-HIF-1α increased SC survival by 34.3%. The increase in cell survival was detectable by stereology, but not by in vivo luciferase or ex vivo GFP IVIS imaging. The results support the hypothesis that activating adaptive cellular pathways enhances transplant survival and identifies an alternative pro-survival approach that, with optimization, could be amenable to clinical translation.