Up-Regulation of CD146 in Schwann Cells Following Peripheral Nerve Injury Modulates Schwann Cell Function in Regeneration

CD146, a therapeutic target involved in cell plasticity

Since its identification as a marker for advanced melanoma in the 1980s, CD146 has been found to have multiple functions in both physiological and pathological processes, including embryonic development, tissue repair and regeneration, tumor progression, fibrosis disease, and inflammations. Subsequent research has revealed that CD146 is involved in various signaling pathways as a receptor or co-receptor in these processes. This correlation between CD146 and multiple diseases has sparked interest in its potential applications in diagnosis, prognosis, and targeted therapy. To better comprehend the versatile roles of CD146, we have summarized its research history and synthesized findings from numerous reports, proposing that cell plasticity serves as the underlying mechanism through which CD146 contributes to development, regeneration, and various diseases. Targeting CD146 would consequently halt cell state shifting during the onset and progression of these related diseases. Therefore, the development of therapy targeting CD146 holds significant practical value.

Single-Cell RNA Sequencing Reveals Dysregulated POSTN+WNT5A+ Fibroblast Subclusters in Prurigo Nodularis

Prurigo nodularis (PN) is an intensely pruritic, inflammatory skin disease with a poorly understood pathogenesis. We performed single-cell transcriptomic profiling of 28,695 lesional and nonlesional PN cells. Lesional PN has increased dysregulated fibroblasts (FBs) and myofibroblasts. FBs in lesional PN were shifted toward a cancer-associated FB-like phenotype, with POSTN+WNT5A+ cancer-associated FBs increased in PN and similarly so in squamous cell carcinoma. A multicenter cohort study revealed an increased risk of squamous cell carcinoma and cancer-associated FB-associated malignancies (breast and colorectal) in patients with PN. Systemic fibroproliferative diseases (renal sclerosis and idiopathic pulmonary fibrosis) were upregulated in patients with PN. Ligand-receptor analyses demonstrated an FB neuronal axis with FB-derived WNT5A and periostin interactions with neuronal receptors melanoma cell adhesion molecule and ITGAV. These findings identify a pathogenic and targetable POSTN+WNT5A+ FB subpopulation that may predispose cancer-associated FB-associated malignancies in patients with PN.

GFP-labeled Schwann cell-like cells derived from hair follicle epidermal neural crest stem cells promote the acellular nerve allografts to repair facial nerve defects in rats

BACKGROUND

Acellular nerve allografts (ANAs) have been successfully applied to bridge facial nerve defects, and transplantation of stem cells may enhance the regenerative results. Up to now, application of hair follicle epidermal neural crest stem cell-derived Schwann cell-like cells (EPI-NCSC-SCLCs) combined with ANAs for bridging facial nerve defects has not been reported.

METHODS

The effect of ANAs laden with green fluorescent protein (GFP)-labeled EPI-NCSC-SCLCs (ANA + cells) on bridging rat facial nerve trunk defects (5-mm-long) was detected by functional and morphological examination, as compared with autografts and ANAs, respectively.

RESULTS

(1) EPI-NCSC-SCLCs had good compatibility with ANAs in vitro. (2) In the ANA + cells group, the GFP signals were observed by in vivo imaging system for small animals within 8 weeks, and GFP-labeled EPI-NCSC-SCLCs were detected in the tissue slices at 16 weeks postoperatively. (3) The facial symmetry at rest after surgery in the ANA + cells group was better than that in the ANA group (p < 0.05), and similar to that in the autograft group (p > 0.05). The initial recovery time of vibrissal and eyelid movement in the ANA group was 2 weeks later than that in the other two groups. (4) The myelinated fibers, myelin sheath thickness and diameter of the axons of the buccal branches in the ANA group were significantly worse than those in the other two groups (P < 0.05), and the results in the ANA + cells group were similar to those in the autograft group (p > 0.05).

CONCLUSIONS

EPI-NCSC-SCLCs could promote functional and morphological recovery of rat facial nerve defects, and GFP labeling could track the transplanted EPI-NCSC-SCLCs in vivo for a certain period of time. These may provide a novel choice for clinical treatment of peripheral nerve defects.

Role of transforming growth factor-β in peripheral nerve regeneration

Injuries caused by trauma and neurodegenerative diseases can damage the peripheral nervous system and cause functional deficits. Unlike in the central nervous system, damaged axons in peripheral nerves can be induced to regenerate in response to intrinsic cues after reprogramming or in a growth-promoting microenvironment created by Schwann cells. However, axon regeneration and repair do not automatically result in the restoration of function, which is the ultimate therapeutic goal but also a major clinical challenge. Transforming growth factor (TGF) is a multifunctional cytokine that regulates various biological processes including tissue repair, embryo development, and cell growth and differentiation. There is accumulating evidence that TGF-β family proteins participate in peripheral nerve repair through various factors and signaling pathways by regulating the growth and transformation of Schwann cells; recruiting specific immune cells; controlling the permeability of the blood-nerve barrier, thereby stimulating axon growth; and inhibiting remyelination of regenerated axons. TGF-β has been applied to the treatment of peripheral nerve injury in animal models. In this context, we review the functions of TGF-β in peripheral nerve regeneration and potential clinical applications.

Promising Markers in the Context of Mesenchymal Stem/Stromal Cells Subpopulations with Unique Properties

The heterogeneity of the mesenchymal stem/stromal cells (MSCs) population poses a challenge to researchers and clinicians, especially those observed at the population level. What is more, the lack of precise evidences regarding MSCs developmental origin even further complicate this issue. As the available evidences indicate several possible pathways of MSCs formation, this diverse origin may be reflected in the unique subsets of cells found within the MSCs population. Such populations differ in specialization degree, proliferation, and immunomodulatory properties or exhibit other additional properties such as increased angiogenesis capacity. In this review article, we attempted to identify such outstanding populations according to the specific surface antigens or intracellular markers. Described groups were characterized depending on their specialization and potential therapeutic application. The reports presented here cover a wide variety of properties found in the recent literature, which is quite scarce for many candidates mentioned in this article. Even though the collected information would allow for better targeting of specific subpopulations in regenerative medicine to increase the effectiveness of MSC-based therapies.

Single-cell RNA sequencing reveals dysregulated fibroblast subclusters in prurigo nodularis

Prurigo nodularis (PN) is an intensely pruritic, chronic inflammatory skin disease that disproportionately affects black patients. However, the pathogenesis of PN is poorly understood. We performed single-cell transcriptomic profiling, ligand receptor analysis and cell trajectory analysis of 28,695 lesional and non-lesional PN skin cells to uncover disease-identifying cell compositions and genetic characteristics. We uncovered a dysregulated role for fibroblasts (FBs) and myofibroblasts as a key pathogenic element in PN, which were significantly increased in PN lesional skin. We defined seven unique subclusters of FBs in PN skin and observed a shift of PN lesional FBs towards a cancer-associated fibroblast (CAF)-like phenotype, with WNT5A+ CAFs increased in the skin of PN patients and similarly so in squamous cell carcinoma (SCC). A multicenter PN cohort study subsequently revealed an increased risk of SCC as well as additional CAF-associated malignancies in PN patients, including breast and colorectal cancers. Systemic fibroproliferative diseases were also upregulated in PN patients, including renal sclerosis and idiopathic pulmonary fibrosis. Ligand receptor analyses demonstrated increased FB1-derived WNT5A and periostin interactions with neuronal receptors MCAM and ITGAV, suggesting a fibroblast-neuronal axis in PN. Type I IFN responses in immune cells and increased angiogenesis/permeability in endothelial cells were also observed. As compared to atopic dermatitis (AD) and psoriasis (PSO) patients, increased mesenchymal dysregulation is unique to PN with an intermediate Th2/Th17 phenotype between atopic dermatitis and psoriasis. These findings identify a pathogenic role for CAFs in PN, including a novel targetable WNT5A+ fibroblast subpopulation and CAF-associated malignancies in PN patients.

Biomechanical microenvironment in peripheral nerve regeneration: from pathophysiological understanding to tissue engineering development

Peripheral nerve injury (PNI) caused by trauma, chronic disease and other factors may lead to partial or complete loss of sensory, motor and autonomic functions, as well as neuropathic pain. Biological activities are always accompanied by mechanical stimulation, and biomechanical microenvironmental homeostasis plays a complicated role in tissue repair and regeneration. Recent studies have focused on the effects of biomechanical microenvironment on peripheral nervous system development and function maintenance, as well as neural regrowth following PNI. For example, biomechanical factors-induced cluster gene expression changes contribute to formation of peripheral nerve structure and maintenance of physiological function. In addition, extracellular matrix and cell responses to biomechanical microenvironment alterations after PNI directly trigger a series of cascades for the well-organized peripheral nerve regeneration (PNR) process, where cell adhesion molecules, cytoskeletons and mechanically gated ion channels serve as mechanosensitive units, mechanical effector including focal adhesion kinase (FAK) and yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ) as mechanotransduction elements. With the rapid development of tissue engineering techniques, a substantial number of PNR strategies such as aligned nerve guidance conduits, three-dimensional topological designs and piezoelectric scaffolds emerge expected to improve the neural biomechanical microenvironment in case of PNI. These tissue engineering nerve grafts display optimized mechanical properties and outstanding mechanomodulatory effects, but a few bottlenecks restrict their application scenes. In this review, the current understanding in biomechanical microenvironment homeostasis associated with peripheral nerve function and PNR is integrated, where we proposed the importance of balances of mechanosensitive elements, cytoskeletal structures, mechanotransduction cascades, and extracellular matrix components; a wide variety of promising tissue engineering strategies based on biomechanical modulation are introduced with some suggestions and prospects for future directions.