Mesenchymal stem cells for sensorineural hearing loss: protocol for a systematic review of preclinical studies

The Detrimental and Beneficial Functions of Macrophages After Cochlear Injury

Macrophages are the main intrinsic immune cells in the cochlea; they can be activated and play a complicated role after cochlear injury. Many studies have shown that the number of macrophages and their morphological characteristics within the major cochlear partitions undergo significant changes under various pathological conditions including acoustic trauma, ototoxic drug treatment, age-related cochlear degeneration, selective hair cell (HC) and spiral ganglion neuron (SGN) elimination, and surgery. However, the exact role of these macrophages after cochlear injury is still unclear. Regulating the migration and activity of macrophages may be a therapeutic approach to reduce the risk or magnitude of trauma-induced hearing loss, and this review highlights the role of macrophages on the peripheral auditory structures of the cochlea and elucidate the mechanisms of macrophage injury and the strategies to reduce the injury by regulating macrophage.

A narrative overview of utilizing biomaterials to recapitulate the salient regenerative features of dental-derived mesenchymal stem cells

Tissue engineering approaches have emerged recently to circumvent many limitations associated with current clinical practices. This elegant approach utilizes a natural/synthetic biomaterial with optimized physiomechanical properties to serve as a vehicle for delivery of exogenous stem cells and bioactive factors or induce local recruitment of endogenous cells for in situ tissue regeneration. Inspired by the natural microenvironment, biomaterials could act as a biomimetic three-dimensional (3D) structure to help the cells establish their natural interactions. Such a strategy should not only employ a biocompatible biomaterial to induce new tissue formation but also benefit from an easily accessible and abundant source of stem cells with potent tissue regenerative potential. The human teeth and oral cavity harbor various populations of mesenchymal stem cells (MSCs) with self-renewing and multilineage differentiation capabilities. In the current review article, we seek to highlight recent progress and future opportunities in dental MSC-mediated therapeutic strategies for tissue regeneration using two possible approaches, cell transplantation and cell homing. Altogether, this paper develops a general picture of current innovative strategies to employ dental-derived MSCs combined with biomaterials and bioactive factors for regenerating the lost or defective tissues and offers information regarding the available scientific data and possible applications.

Robust preclinical evidence in somatic cell genome editing: A key driver of responsible and efficient therapeutic innovations

Somatic cell genome editing (SCGE) is highly promising for therapeutic innovation. This study demonstrates that the majority of 46 preclinical SCGE studies discussed in reviews as particularly promising for clinical translation do not report on key elements for robust and confirmatory research practices: randomization, blinding, sample size calculation, data handling, pre-registration, multi-centric study design, and independent confirmation. We present the here-examined reporting standards and the new National Institutes of Health (NIH) funding criteria for SCGE research as a viable solution to protect this promising field from backlashes. We argue that the implementation of the novel methodological standards provides the opportunity for SCGE research to become a lighthouse example for trustworthy and useful translational research.

Hearing Phenotypes of Patients with Hearing Loss Homozygous for the GJB2 c.235delc Mutation

Hereditary hearing loss is characterized by remarkable phenotypic heterogeneity. Patients with the same pathogenic mutations may exhibit various hearing loss phenotypes. In the Chinese population, the c.235delC mutation is the most common pathogenic mutation of GJB2 and is closely related to hereditary recessive hearing loss. Here, we investigated the hearing phenotypes of patients with hearing loss associated with the homozygous c.235delC mutation, paying special attention to asymmetric interaural hearing loss. A total of 244 patients with the GJB2 c.235delC homozygous mutation encountered from 2007 to 2015 were enrolled. The severity of hearing loss was scaled with the American Speech-Language-Hearing Association (ASHA). Auditory phenotypes were analyzed, and three types of interaural asymmetry were defined based on audiograms: Type A (asymmetry of hearing loss severity), Type B (asymmetry of audiogram shape), and Type C (Type A plus Type B). Of the 488 ears (244 cases) examined, 71.93% (351) presented with profound hearing loss, 14.34% (70) with severe hearing loss, and 9.43% (46) with moderate to severe hearing loss. The most common audiogram shapes were descending (31.15%) and flat (24.18%). A total of 156 (63.93%) of the 244 patients exhibited asymmetric interaural hearing loss in terms of severity and/or audiogram shape. Type A was evident in 14 of these cases, Type B in 106, and Type C in 36. In addition, 211 of 312 ears (67.63%) in the interaural hearing asymmetry group showed profound hearing loss, and 59 (18.91%) exhibited severe hearing loss, with the most common audiogram shapes being flat (27.88%) and descending (22.12%). By contrast, in the interaural hearing symmetry group, profound hearing loss was observed in 140 ears (79.55%), and the most common audiograms were descending (46.59%) and residual (21.59%). Hearing loss associated with the GJB2 c.235delC homozygous mutation shows diverse phenotypes, and a considerable proportion of patients show bilateral hearing loss asymmetry.

Mesenchymal stem cells for sensorineural hearing loss: a systematic review of preclinical studies

Sensorineural hearing loss (SNHL) is the most common form of hearing loss that is routinely treated with hearing aids or cochlear implants. Advances in regenerative medicine have now led to animal studies examining the possibility of restoring injured hair cells with mesenchymal stem/stromal cell (MSC) administration. We conducted a systematic review and meta-analysis to collate the existing preclinical literature evaluating MSCs as a treatment for SNHL and quantify the effect of MSCs on functional hearing. Our protocol was published online on CAMARADES. Searches were conducted in four medical databases by two independent investigators. Twelve studies met inclusion and were evaluated for risk of bias using SYRCLE. Rodent models were commonly used (n = 8, 66%), while auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAE) were the most frequent measures assessing hearing loss. MSCs were derived from multiple tissue sources, including bone marrow, adipose tissue, and umbilical cord blood and the dose ranged from 4 × 10³ to 1 × 10⁷ cells. Treatment with MSCs resulted in an improvement in ABR and DPOAE (mean difference-15.22, + 9.10, respectively). Despite high heterogeneity and multiple "unclear" domains in the risk of bias, this review provides evidence that MSCs may have a beneficial effect in hearing function.

Mechanisms of action of molecules with anti-TNF-alpha activity on intestinal barrier inflammation: A systematic review protocol

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha), among cytokines that mediate the inflammatory process, plays an important role in diseases involving the loss of intestinal barrier integrity. Several molecules with anti-TNF-alpha activity have been studied aiming to develop new therapies. The purpose of this paper is to describe the systematic review protocol of experimental studies that determine mechanisms of action of molecules with anti-TNF-alpha activity on intestinal barrier inflammation.

METHODS

This protocol is guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes Protocols (PRISMA-P). The databases to be searched are PubMed, EMBASE, Scopus, ScienceDirect, and Web of Science. Experimental studies in rats or mice that assessed the activity of anti-TNF-alpha molecules in models of intestinal barrier inflammation will be included in the systematic review. Studies characteristics, experimental model, and main results will be described and the bias risk assessment will be performed. Two independent reviewers will perform study selection, data extraction, and methodological quality assessment. A narrative synthesis will be made for the included studies. Also, if sufficient data is available, a meta-analysis will be conducted. I statistics will be used to assess heterogeneity.

RESULTS

The present protocol will assist in producing a systematic review that identifies the mechanisms underlying the reduction of TNF-alpha in intestinal barrier inflammation models.

CONCLUSION

The systematic review may contribute to the theoretical basis of research on new molecules with anti-TNF-alpha potential and, consequently, in the development of new therapies employed in humans.

PROSPERO REGISTRATION NUMBER

CRD42019131862.