Human Plasma Rich in Growth Factors Improves Survival and Neurite Outgrowth of Spiral Ganglion Neurons In Vitro

Extracellular Vesicles in Inner Ear Therapies-Pathophysiological, Manufacturing, and Clinical Considerations

(1) Background: Sensorineural hearing loss is a common and debilitating condition. To date, comprehensive pharmacologic interventions are not available. The complex and diverse molecular pathology that underlies hearing loss may limit our ability to intervene with small molecules. The current review foccusses on the potential for the use of extracellular vesicles in neurotology. (2) Methods: Narrative literature review. (3) Results: Extracellular vesicles provide an opportunity to modulate a wide range of pathologic and physiologic pathways and can be manufactured under GMP conditions allowing for their application in the human inner ear. The role of inflammation in hearing loss with a focus on cochlear implantation is shown. How extracellular vesicles may provide a therapeutic option for complex inflammatory disorders of the inner ear is discussed. Additionally, manufacturing and regulatory issues that need to be addressed to develop EVs as advanced therapy medicinal product for use in the inner ear are outlined. (4) Conclusion: Given the complexities of inner ear injury, novel therapeutics such as extracellular vesicles could provide a means to modulate inflammation, stress pathways and apoptosis in the inner ear.

Evaluation of Platelet-Rich Plasma Therapy for Peripheral Nerve Regeneration: A Critical Review of Literature

Peripheral nerve injury (PNI) is a common disease in clinic, and the regeneration process of peripheral nerve tissue is slow, and patients with PNI often suffer from the loss of nerve function. At present, related research on the mechanism of peripheral nerve regeneration has become a hot spot, and scholars are also seeking a method that can accelerate the regeneration of peripheral nerve. Platelet-rich plasma (PRP) is a platelet concentrate extracted from autologous blood by centrifugation, which is a kind of bioactive substance. High concentration of platelets can release a variety of growth factors after activation, and can promote the proliferation and differentiation of tissue cells, which can accelerate the process of tissue regeneration. The application of PRP comes from the body, there is no immune rejection reaction, it can promote tissue regeneration with less cost, it is,therefore, widely used in various clinical fields. At present, there are relatively few studies on the application of PRP to peripheral nerve regeneration. This article summarizes the literature in recent years to illustrate the effect of PRP on peripheral nerve regeneration from mechanism to clinical application, and prospects for the application of PRP to peripheral nerve.

Personalized Proteomics for Precision Diagnostics in Hearing Loss: Disease-Specific Analysis of Human Perilymph by Mass Spectrometry

Despite a vast amount of data generated by proteomic analysis on cochlear fluid, novel clinically applicable biomarkers of inner ear diseases have not been identified hitherto. The aim of the present study was to analyze the proteome of human perilymph from cochlear implant patients, thereby identifying putative changes of the composition of the cochlear fluid perilymph due to specific diseases. Sampling of human perilymph was performed during cochlear implantation from patients with clinically or radiologically defined inner ear diseases like enlarged vestibular aqueduct (EVA; n = 14), otosclerosis (n = 10), and Ménière's disease (n = 12). Individual proteins were identified by a shotgun proteomics approach and data-dependent acquisition, thereby revealing 895 different proteins in all samples. Based on quantification values, a disease-specific protein distribution in the perilymph was demonstrated. The proteins short-chain dehydrogenase/reductase family 9C member 7 and esterase D were detected in nearly all samples of Ménière's disease patients, but not in samples of patients suffering from EVA and otosclerosis. The presence of both proteins in the inner ear tissue of adult mice and neonatal rats was validated by immunohistochemistry. Whether these proteins have the potential for a biomarker in the perilymph of Ménière's disease patients remains to be elucidated.

Autologous Platelet- and Extracellular Vesicle-Rich Plasma Is an Effective Treatment Modality for Chronic Postoperative Temporal Bone Cavity Inflammation: Randomized Controlled Clinical Trial

Purpose

To determine the efficacy of autologous platelet- and extracellular vesicle-rich plasma (PVRP) to treat chronic postoperative temporal bone cavity inflammation (CPTBCI) after exhausting surgical and standard conservative therapies.

Materials and Methods

Patients were randomly allocated to treatment with PVRP (PVRP group) or standard conservative methods (control group) in a setting of four once-monthly checkups and subsequent follow-up. The treatment outcome was measured with the Chronic Otitis Media Questionnaire-12 (COMQ-12), CPTBCI focus surface area, and CPTBCI symptom-free time after the fourth checkup.

Results

Eleven patients from each group completed the trial; 95% of patients suffered from chronically discharging mastoid cavity (the type of CPTBCI). Within four checkups, the COMQ-12 score decreased statistically significantly in the PVRP group (p < 0.001) but not in the control group (p = 0.339). The CPTBCI foci surface area decreased statistically significantly between the first and second checkups (p < 0.0005) but not between other checkups (p > 0.05) in the PVRP group. No statistically significant differences in CPTBCI foci surface area were detected between checkups in the control group (p = 0.152). Nine patients from the PVRP group and three patients from the control group were CPTBCI symptom-free at the fourth checkup. The median symptom-free time was 9.2 months (95% CI [7.4, 11.9]) in the PVRP group. Cumulatively, 49% of patients in the PVRP group remained CPTBCI symptom-free for 12.7 months after the fourth checkup.

Conclusion

Autologous PVRP represents a novel additional and successful treatment modality for a chronically discharging radical mastoid cavity when the surgical and standard conservative treatment methods have been exhausted.

Trial Number

https://clinicaltrials.gov (NCT04281901).

Potentiation of Brain-Derived Neurotrophic Factor-Induced Protection of Spiral Ganglion Neurons by C3 Exoenzyme/Rho Inhibitor

Preservation of the excitability of spiral ganglion neurons (SGN) may contribute to an improved speech perception after cochlear implantation. Thus, the application of exogenous neurotrophic factors such as the neurotrophin brain-derived neurotrophic factor (BDNF) to increase SGN survival in vitro and in vivo is a promising pharmacological approach in cochlear implant (CI) research. Due to the difficult pharmacokinetic profile of proteins such as BDNF, there is a quest for small molecules to mediate the survival of SGN or to increase the efficacy of BDNF. The C3 exoenzyme from Clostridium botulinum could be a potential new candidate for the protection and regeneration of SGN. Inhibition of the RhoA GTPase pathway which can be mediated by C3 is described as a promising strategy to enhance axonal regeneration and to exert pro-survival signals in neurons. Nanomolar concentrations of C3, its enzymatically inactive form C3^E174Q, and a 26mer C-terminal peptide fragment covering amino acid 156–181 (C3^156-181) potentiated the neuroprotective effect on SGN mediated by BDNF in vitro. The neuroprotective effect of C3/BDNF was reduced to the neuroprotective effect of BDNF alone after the treatment with wortmannin, an inhibitor of the phosphatidylinositol-3-kinase (PI3K).The exoenzyme C3 (wild-type and enzyme-deficient) and the C3 peptide fragment C3^154–181 present novel biologically active compounds for the protection of the SGN. The exact underlying intracellular mechanisms that mediate the neuroprotective effect are not clarified yet, but the combination of BDNF (TrkB stimulation) and C3 exoenzyme (RhoA inhibition) can be used to protect SGN in vitro.

Effects of Platelet-Rich Plasma on Cellular Populations of the Central Nervous System: The Influence of Donor Age

Platelet-rich plasma (PRP) is a biologic therapy that promotes healing responses across multiple medical fields, including the central nervous system (CNS). The efficacy of this therapy depends on several factors such as the donor's health status and age. This work aims to prove the effect of PRP on cellular models of the CNS, considering the differences between PRP from young and elderly donors. Two different PRP pools were prepared from donors 65‒85 and 20‒25 years old. The cellular and molecular composition of both PRPs were analyzed. Subsequently, the cellular response was evaluated in CNS in vitro models, studying proliferation, neurogenesis, synaptogenesis, and inflammation. While no differences in the cellular composition of PRPs were found, the molecular composition of the Young PRP showed lower levels of inflammatory molecules such as CCL-11, as well as the presence of other factors not found in Aged PRP (GDF-11). Although both PRPs had effects in terms of reducing neural progenitor cell apoptosis, stabilizing neuronal synapses, and decreasing inflammation in the microglia, the effect of the Young PRP was more pronounced. In conclusion, the molecular composition of the PRP, conditioned by the age of the donors, affects the magnitude of the biological response.

Extracellular vesicles from human multipotent stromal cells protect against hearing loss after noise trauma in vivo

The lack of approved anti-inflammatory and neuroprotective therapies in otology has been acknowledged in the last decades and recent approaches are heralding a new era in the field. Extracellular vesicles (EVs) derived from human multipotent (mesenchymal) stromal cells (MSC) can be enriched in vesicular secretome fractions, which have been shown to exert effects (eg, neuroprotection and immunomodulation) of their parental cells. Hence, MSC-derived EVs may serve as novel drug candidates for several inner ear diseases. Here, we provide first evidence of a strong neuroprotective potential of human stromal cell-derived EVs on inner ear physiology. In vitro, MSC-EV preparations exerted immunomodulatory activity on T cells and microglial cells. Moreover, local application of MSC-EVs to the inner ear significantly attenuated hearing loss and protected auditory hair cells from noise-induced trauma in vivo. Thus, EVs derived from the vesicular secretome of human MSC may represent a next-generation biological drug that can exert protective therapeutic effects in a complex and nonregenerating organ like the inner ear.