Auditory and vestibular mechanosensory hair cells in the adult mammalian inner ear do not regenerate following injury or ageing, inducing irreversible hearing loss and balance disorders for millions of people. Research on model systems showing replacement of mechanosensory cells can provide mechanistic insight to develop new regenerative therapies. Here we developed new lineage tracing systems to reveal the generation of mechanosensory neurons (Johnston's Organ, JO) in the antennae of intact adult Drosophila. New JO neurons develop cilia, express an essential mechano-transducer gene and target central brain circuitry. Furthermore, we identified low-level JO self-replication as a new mechanism of neuronal plasticity. Overall, our findings introduce a new platform to expedite the research of mechanisms and compounds mediating mechanosensory cell regeneration.
Background: Although electrical stimulation (ES) can improve nerve regeneration, the impact of nerve block, such as lidocaine (Lido), on the therapeutic benefits of ES remains unclear. We used a rat tibial nerve transection-and-repair model to explore how either preoperative (PreOp) or postoperative (PostOp) nerve block affects ES-related improvement in regeneration. Methods: Lewis rats were used in 1 of 2 studies. The first evaluated the effects of extraneural Lido on both healthy and injured nerves. In the second study, rats were randomized to 5 experimental groups: No ES (negative control), PreOp Lido, ES + PreOp Lido, PostOp + ES, and ES (positive control). All groups underwent tibial nerve transection and repair. In both studies, nerves were harvested for histological analysis of regeneration distal to the injury site. Results: Application of extraneural Lido did not damage healthy or injured nerve based on qualitative histological observations. In the context of nerve transection and repair, the ES group exhibited improved axon regeneration at 21 days measured by the total number of myelinated fibers compared with No ES. Fiber density and percentage of neural tissue in the ES group were greater than those in both No ES and PreOp Lido + ES groups. ES + PostOp Lido was not different from No ES or ES group. Conclusions: Extraneural application of Lido did not damage nerves. Electrical stimulation augmented nerve regeneration, but Lido diminished the ES-related improvement in nerve regeneration. Clinical studies on the effects of ES to nerve regeneration may need to consider nerve block as a variable affecting ES outcome.
Auditory and vestibular mechanosensory hair cells do not regenerate following injury or aging in the adult mammalian inner ear, inducing irreversible hearing loss and balance disorders for millions of people. Research on model systems showing replacement of mechanosensory cells can provide mechanistic insights into developing new regenerative therapies. Here, we developed lineage tracing systems to reveal the generation of mechanosensory neurons in the Johnston's Organ (JO) of intact adult Drosophila, which are the functional counterparts to hair cells in vertebrates. New JO neurons develop cilia and target central brain circuitry. Unexpectedly, mitotic recombination clones point to JO neuron self-replication as a likely source of neuronal plasticity. This mechanism is further enhanced upon treatment with experimental and ototoxic compounds. Our findings introduce a new platform to expedite research on mechanisms and compounds mediating mechanosensory cell regeneration, with nascent implications for hearing and balance restoration.
OBJECTIVES/GOALS: We have created the first-ever database for all patients who have acute peripheral nerve injuries. Our goal is to use this data to construct two clinical scoring systems to facilitate triaging by emergency room physicians by 1.) identifying patients who would likely benefit from a nerve surgery, and 2.) identify patients who are less likely to follow up. METHODS/STUDY POPULATION: Based on 2,606 consult emails from the Washington University in St. Louiss Division of Plastic and Reconstructive Surgery, from 2013 to 2019, we have identified more than 600 patient cases in which patients presented after an injury with any kind of nerve deficit. We have defined nerve deficits as any abnormality on motor or sensory exam of the extremities, excluding those younger than 18 years old and those with other disease processes that may affect function of the peripheral nervous system. Data for these patients was collected from electronic medical records and include handedness, nerve injured, operative details, area deprivation index decile, mechanism of injury, insurance and employment status, and whether injuries were a result of work or violence. RESULTS/ANTICIPATED RESULTS: Our plan is to provide the first descriptive statistics for such a population, as well as multiple regression analysis for our two endpoints, loss to follow up and need for surgery. Following regression analysis, we also look to perform cluster analysis to further study co-occurring clinical and social features that affect our endpoints. We are excitedly awaiting to perform the analysis after the final data has been collected. DISCUSSION/SIGNIFICANCE: Nerve injury is a common symptom of penetrating injuries. Many of the socioeconomic factors associated with increased risk for violent injury are also risk factors for decreased rates of follow up. This problem is particularly worrisome given that nerve repair surgery is only viable as an option to return function within the first year after injury.
Introduction/Aims
Repaired nerve injuries can fail to achieve functional recovery. Therapeutic options beyond surgery, such as systemic tacrolimus (FK506) and electrical stimulation (E‐stim), can improve recovery. We tested whether dual administration of FK506 and E‐stim enhances regeneration and recovery more than either therapeutic alone.
Methods
Rats were randomized to four groups: E‐stim, FK506, FK506 + E‐stim, and repair alone. All groups underwent tibial nerve transection and repair. Two sets of animals were created to measure outcomes of early nerve regeneration using nerve histology (n = 36) and functional recovery (n = 42) (21‐ and 42‐day endpoints, respectively). Functional recovery was measured by behavioral analyses (walking track and grid walk) and, at the endpoint, muscle mass and force.
Results
Dual E‐stim and FK506 administration produced histomorphometric measurements of nerve regeneration no different than either therapeutic alone. All treatments were superior to repair alone (FK506, P < .0001; E‐stim, P < .05; FK506 + E‐stim, P < .05). The E‐stim and FK506 + E‐stim groups had improved behavioral recovery compared with repair alone (at 6 weeks: E‐stim, P < .05; FK506 + E‐stim, P < .01). The FK506 group had improved recovery based on walking‐track analysis (at 6 weeks: P < .001) and muscle force and mass (P < .05). The concurrent use of both therapies ensured earlier functional recovery and decreased variability in functional outcomes compared with either therapy alone, suggesting a moderate benefit.
Discussion
Dual administration of FK506 and E‐stim showed minimal additive effects to further improve regeneration or recovery compared with either therapy alone. The data suggest the combination of FK506 and E‐stim appears to combine the relative strengths of each therapeutic.
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