Combination of BMSCs-laden acellular nerve xenografts transplantation and G-CSF administration promotes sciatic nerve regeneration

Exploring miR-21 as a key regulator in two distinct approaches of bone marrow stromal cells differentiation into Schwann-like cells

The differentiation of bone marrow stromal cells (BMSCs) into Schwann-like cells (SCLCs) has the potential to promote the structural and functional restoration of injured axons. However, the optimal induction protocol and its underlying mechanisms remain unclear. This study aimed to compare the effectiveness of different induction protocols in promoting the differentiation of rat BMSCs into SCLCs and to explore their potential mechanisms. BMSCs were induced using two distinct methods: a composite factor induction approach (Protocol-1) and a conditioned culture medium induction approach (Protocol-2). The expression of Schwann cells (SCs) marker proteins and neurotrophic factors (NTFs) in the differentiated cells was assessed. Cell proliferation and apoptosis were also measured. During induction, changes in miR-21 and Sprouty RTK signaling antagonist 2 (SPRY2) mRNA were analyzed. Following the transfection of BMSCs with miR-21 agomir or miR-21 antagomir, induction was carried out using both protocols, and the expression of SPRY2, ERK1/2, and SCs marker proteins was examined. The results revealed that NTFs expression was higher in Protocol-1, whereas SCs marker proteins expression did not significantly differ between the two groups. Compared to Protocol-1, Protocol-2 exhibited enhanced cell proliferation and fewer apoptotic and necrotic cells. Both protocols showed a negative correlation between miR-21 and SPRY2 expression throughout the induction stages. After induction, the miR-21 agomir group exhibited reduced SPRY2 expression, increased ERK1/2 expression, and significantly elevated expression of SCs marker proteins. This study demonstrates that Protocol-1 yields higher NTFs expression, whereas Protocol-2 results in stronger SCLCs proliferation. Upregulating miR-21 suppresses SPRY2 expression, activates the ERK1/2 signaling pathway, and promotes BMSC differentiation into SCLCs.

Crosstalk between Bone and Nerves within Bone

For the past two decades, the function of intrabony nerves on bone has been a subject of intense research, while the function of bone on intrabony nerves is still hidden in the corner. In the present review, the possible crosstalk between bone and intrabony peripheral nerves will be comprehensively analyzed. Peripheral nerves participate in bone development and repair via a host of signals generated through the secretion of neurotransmitters, neuropeptides, axon guidance factors and neurotrophins, with additional contribution from nerve-resident cells. In return, bone contributes to this microenvironmental rendezvous by housing the nerves within its internal milieu to provide mechanical support and a protective shelf. A large ensemble of chemical, mechanical, and electrical cues works in harmony with bone marrow stromal cells in the regulation of intrabony nerves. The crosstalk between bone and nerves is not limited to the physiological state, but also involved in various bone diseases including osteoporosis, osteoarthritis, heterotopic ossification, psychological stress-related bone abnormalities, and bone related tumors. This crosstalk may be harnessed in the design of tissue engineering scaffolds for repair of bone defects or be targeted for treatment of diseases related to bone and peripheral nerves.

Combinatory transplantation of mesenchymal stem cells with flavonoid small molecule in acellular nerve graft promotes sciatic nerve regeneration

Previous animal studies have demonstrated that the flavonoid small-molecule TrkB agonist, 7, 8-dihydroxyflavone (DHF), promotes axon regeneration in transected peripheral nerves. In the present study, we investigated the combined effects of 7, 8-DHF treatment and bone marrow-derived stem/stromal cells (BMSCs) engraftment into acellular nerve allografts (ANAs) and explore relevant mechanisms that may be involved. Our results show that TrkB and downstream ERK1/2 phosphorylation are increased upon 7, 8-DHF treatment compared to the negative control group. Also, 7, 8-DHF promotes proliferation, survival, and Schwann-like cell differentiation of BMSCs in vitro. While selective ERK1/2 inhibitor U0126 suppressed the effect of upregulation of ERK1/2 phosphorylation and decreased cell proliferation, survival, and Schwann-like cell differentiation partially induced by 7, 8-DHF. In vivo, 7, 8-DHF promotes survival of transplanted BMSCs and upregulates axonal growth and myelination in regenerating ANAs. 7, 8-DHF+BMSCs also improved motor endplate density of target musculature. These benefits were associated with increased motor functional recovery. 7, 8-DHF+BMSCs significantly upregulated TrkB and ERK1/2 phosphorylation expression in regenerating ANA, and increased TrkB expression in the lumbar spinal cord. The mechanism of 7, 8-DHF action may be related to its ability to upregulate TrkB signaling, and downstream activation of survival signaling molecules ERK1/2 in the regenerating ANAs and spinal cord and improved survival of transplanted BMSCs. This study provides novel foundational data connecting the benefits of 7, 8-DHF treatment in neural injury and repair to BMSCs biology and function and demonstrates a potential combination approach for the treatment of injured peripheral nerve via nerve graft transplant.

The Combination of Adipose-derived Schwann-like Cells and Acellular Nerve Allografts Promotes Sciatic Nerve Regeneration and Repair through the JAK2/STAT3 Signaling Pathway in Rats

Schwann cells (SCs) combined with acellular nerve allografts (ANAs) effectively promote the regeneration and repair of peripheral nerves, but the exact mechanism has not been fully elucidated. However, the disadvantages of SCs include their limited source and slow rate of expansion in vitro. Previous studies have found that adipose-derived stem cells have the ability to differentiate into Schwann-like cells. Therefore, we speculated that Schwann-like cells combined with ANAs could profoundly facilitate nerve regeneration and repair. The aim of the present study was to investigate the cellular and molecular mechanisms of regeneration and repair. In this study, tissue-engineered nerves were first constructed by adipose-derived Schwann-like cells and ANAs to bridge missing sciatic nerves. Then, the rats were randomly divided into five groups (n = 12 per group): a Control group; a Model group; an ADSC group; an SC-L group; and a DMEM group. Twelve weeks postsurgery, behavioral function tests and molecular biological techniques were used to evaluate the function of regenerated nerves and the relevant molecular mechanisms after sciatic nerve injury (SNI). The results showed that adipose-derived Schwann-like cells combined with ANAs markedly promoted sciatic nerve regeneration and repair. These findings also demonstrated that the expression of neurotrophic factors (NFs) was increased, and the expression of Janus activated kinase2 (JAK2)/P-JAK2, signal transducer and activator of transcription-3 (STAT3)/P-STAT3 was decreased in the spinal cord after SNI. Therefore, these results suggested that highly expressed NFs in the spinal cord could promote nerve regeneration and repair by inhibiting activation of the JAK2/STAT3 signaling pathway.