Site-Specific RNA Editing of Stop Mutations in the CFTR mRNA of Human Bronchial Cultured Cells

It is reported that about 10% of cystic fibrosis (CF) patients worldwide have nonsense (stop) mutations in the CFTR gene, which cause the premature termination of CFTR protein synthesis, leading to a truncated and non-functional protein. To address this issue, we investigated the possibility of rescuing the CFTR nonsense mutation (UGA) by sequence-specific RNA editing in CFTR mutant CFF-16HBEge, W1282X, and G542X human bronchial cells. We used two different base editor tools that take advantage of ADAR enzymes (adenosine deaminase acting on RNA) to edit adenosine to inosine (A-to-I) within the mRNA: the REPAIRv2 (RNA Editing for Programmable A to I Replacement, version 2) and the minixABE (A to I Base Editor). Immunofluorescence experiments show that both approaches were able to recover the CFTR protein in the CFTR mutant cells. In addition, RT-qPCR confirmed the rescue of the CFTR full transcript. These findings suggest that site-specific RNA editing may efficiently correct the UGA premature stop codon in the CFTR transcript in CFF-16HBEge, W1282X, and G542X cells. Thus, this approach, which is safer than acting directly on the mutated DNA, opens up new therapeutic possibilities for CF patients with nonsense mutations

Cholinergic control of cell growth and migration in undifferentiated and schwann cell–like differentiated adipose-mesenchimal stem cells.

Peripheral nerve injury is a common disease and represents a major economic burden for society. The development of novel strategies, including cell therapy, to enhance peripheral nerve regeneration is therefore of great social and clinical relevance. The use of synthetic nerve conduits, in combination with different cell types may represent a promising therapy. The great regenerative capacity of peripheral nervous system (PNS) is due to a permissive environment provided by Schwann cells that proliferate, migrate and release growth factors either during development or after nerve lesions. Mesenchimal stem cells (MSCs) are an attractive cell source for nerve tissue regeneration. They are able to self-renew and possess multi potent differentiation properties. In particular adipose MSCs (A-MSCs) appear the most promising source of MSCs. Recent studies have shown that A-MSCs can be differentiated in Schwann-like cells, representing an alternative and reliable source of peripheral glial cells. Acetylcholine (ACh), the main neurotransmitter in central and PNS, has the property to modulate neurite outgrowth and to control Schwann cell proliferation and differentiation. ACh plays important role also in non-neural tissue, but its functions in mesenchymal stem cells (MSC) has been poorly investigated. In present work we have characterized the muscarinic cholinergic agonist effects in rat A-MSC and in differentiated Schwann-like obtained from A-MSCs. Analysis by RT-PCR has demonstrated that the A-MSCs express all muscarinic receptor subtypes. MTT analysis and wound healing assay have also demonstrated that the selective activation of M2 receptors caused an inhibition of cell growth and migration of MSCs indicating the ACh as possible modulator of MSC proliferation and migration. In Schwann cell-like derived from A-MSC, similarly to that observed in Schwann cells, the M2 muscarinic agonist caused a decrease of cell proliferation without affecting cell survival. Further analysis are addressed to evaluate the capability of these receptors to mediate the differentiative processes in Schwann cell-like, as previously observed in Schwann cells. In conclusion, we hypothesize that a combination of autologous MSC, differentiated in Schwann-like, and selective ACh mimetics may represent a successful strategy to achieve better results in peripheral nerve regeneration

M2 receptor activation controls cell growth, migration and differentiation of rat adipose-mesenchimal stem cells

The use of synthetic nerve conduits, in combination with different cell types may represent a promising therapy for the peripheral nerve injuries. The great regenerative capacity of peripheral nervous system (PNS) is due to a permissive environment provided by Schwann cells that proliferate, migrate and release growth factors, either during development or after nerve lesions. Mesenchimal stem cells (MSCs) are an attractive cell source for nerve tissue regeneration. They are able to self-renew and possess multi potent differentiation properties. In particular, adipose MSCs (A-MSCs) appear the most promising source of MSCs. Recent studies have shown that A-MSCs can be differentiated in Schwann-like cells, representing an alternative and reliable source of peripheral glial cells. Acetylcholine (ACh), the main neurotransmitter in central and PNS, has the property to modulate neurite outgrowth and to control Schwann cell proliferation and differentiation. ACh plays important role also in non-neural tissue, but its function in MSC has been poorly investigated. In present work we have characterized the muscarinic cholinergic agonist effects in rat A-MSC and in differentiated Schwann-like derived from A-MSCs. Analysis by RTPCR, western blot and immunocytochemistry analysis have demonstrated that the A-MSCs express several muscarinic receptor subtypes. MTT analysis and wound healing assay have also demonstrated that the selective activation of M2 receptors caused an inhibition of cell growth and migration of MSCs, indicating the ACh as possible modulator of MSC proliferation and migration. In Schwann cell-like derived from A-MSC, similarly to that observed in Schwann cells, the M2 muscarinic agonist caused a decrease of cell proliferation without affecting cell survival. Further analysis are addressed to evaluate the capability of these receptors to mediate the differentiative processes in Schwann cell-like, as previously observed in Schwann cells, with particular attention to in vitro myelination. In conclusion, we hypothesize that a combination of autologous MSC, differentiated in Schwann cell-like, and selective ACh-mimetics may represent a successful strategy to achieve better results in peripheral nerve regeneration.The use of synthetic nerve conduits, in combination with different cell types may represent a promising therapy for the peripheral nerve injuries. The great regenerative capacity of peripheral nervous system (PNS) is due to a permissive environment provided by Schwann cells that proliferate, migrate and release growth factors, either during development or after nerve lesions. Mesenchimal stem cells (MSCs) are an attractive cell source for nerve tissue regeneration. They are able to self-renew and possess multi potent differentiation properties. In particular, adipose MSCs (A-MSCs) appear the most promising source of MSCs. Recent studies have shown that A-MSCs can be differentiated in Schwann-like cells, representing an alternative and reliable source of peripheral glial cells. Acetylcholine (ACh), the main neurotransmitter in central and PNS, has the property to modulate neurite outgrowth and to control Schwann cell proliferation and differentiation. ACh plays important role also in non-neural tissue, but its function in MSC has been poorly investigated. In present work we have characterized the muscarinic cholinergic agonist effects in rat A-MSC and in differentiated Schwann-like derived from A-MSCs. Analysis by RTPCR, western blot and immunocytochemistry analysis have demonstrated that the A-MSCs express several muscarinic receptor subtypes. MTT analysis and wound healing assay have also demonstrated that the selective activation of M2 receptors caused an inhibition of cell growth and migration of MSCs, indicating the ACh as possible modulator of MSC proliferation and migration. In Schwann cell-like derived from A-MSC, similarly to that observed in Schwann cells, the M2 muscarinic agonist caused a decrease of cell proliferation without affecting cell survival. Further analysis are addressed to evaluate the capability of these receptors to mediate the differentiative processes in Schwann cell-like, as previously observed in Schwann cells, with particular attention to in vitro myelination. In conclusion, we hypothesize that a combination of autologous MSC, differentiated in Schwann cell-like, and selective ACh-mimetics may represent a successful strategy to achieve better results in peripheral nerve regeneration

M2 muscarinic receptor activation inhibits cell proliferation and migration of rat adipose-mesenchymal stem cells

Mesenchymal stem cells (MSCs), also known as stromal mesenchymal stem cells, are multipotent cells, which can be found in many tissues and organs as bone marrow, adipose tissue and other tissues. In particular MSCs derived from Adipose tissue (ADSCs) are the most frequently used in regenerative medicine because they are easy to source, rapidly expandable in culture and excellent differentiation potential into adipocytes, chondrocytes, and other cell types. Acetylcholine (ACh), the most important neurotransmitter in Central nervous system (CNS) and peripheral nervous system (PNS), plays important roles also in non-neural tissue, but its functions in MSCs are still not investigated. Although MSCs express muscarinic receptor subtypes, their role is completely unknown. In the present work muscarinic cholinergic effects were characterized in rat ADSCs. Analysis by RT-PCR demonstrates that ADSCs express M1-M4 muscarinic receptor subtypes, whereas M2 is one of the most expressed subtype. For this reason, our attention was focused on M2 subtype. By using the selective M2 against Arecaidine Propargyl Ester (APE) we performed cell proliferation and migration assays demonstrating that APE causes cell growth and migration inhibition without affecting cell survival. Our results indicate that ACh via M2 receptors, may contribute to the maintaining of the ADSCs quiescent status. These data are the first evidence that ACh, via muscarinic receptors, might contribute to control ADSCs physiology

RNA Editing Approaches for the correction of nonsense mutation in a cell model for Cystic Fibrosis

Cystic Fibrosis (CF) is an autosomal recessive disease caused by mutations in the CFTR gene. In particular, CFTR nonsense (STOP) mutations generate a premature termination codon (PTC) in the mRNA, leading to the production of a shortened and non-functional protein1. Currently, there is no pharmacological therapy that specifically targets nonsense mutations in CF. In this regard, we are exploring the possibility to correct the PTC using different RNA-based editing tools. These systems exploit the Adenosine Deaminases Acting on RNA (ADAR) to convert the adenosine within the PTC into inosine and allow the full-length protein synthesis2. Among these, a compact REPAIRv2 system uses a modified and truncated dCAS13x.1 fused with ADAR2DD that is recruited to the adenosine of PTC by means of a specifically designed guide RNA1. A different system named RESTORE uses specific antisense RNA oligonucleotides (ASOs), complementary to the CFTR mRNA region with the PTC, except for a cytidine-adenosine mismatch that promotes ADAR recruitment3. In addition, we also evaluated phenotypical anomalies of CFTR mutated cells showing morphological differences in comparison to wild type cells4. Our results pave the way to new therapeutical strategies potentially able to correct the nonsense mutations in cystic fibrosis

GABA-B1 Receptor-Null Schwann Cells Exhibit Compromised In Vitro Myelination

GABA-B receptors are important for Schwann cell (SC) commitment to a non-myelinating phenotype during development. However, the P0-GABA-B1fl/fl conditional knockout mice, lacking the GABA-B1 receptor specifically in SCs, also presented axon modifications, suggesting SC non-autonomous effects through the neuronal compartment. In this in vitro study, we evaluated whether the specific deletion of the GABA-B1 receptor in SCs may induce autonomous or non-autonomous cross-changes in sensory dorsal root ganglia (DRG) neurons. To this end, we performed an in vitro biomolecular and transcriptomic analysis of SC and DRG neuron primary cultures from P0-GABA-B1fl/fl mice. We found that cells from conditional P0-GABA-B1fl/fl mice exhibited proliferative, migratory and myelinating alterations. Moreover, we found transcriptomic changes in novel molecules that are involved in peripheral neuron-SC interaction