Mitochondrial Transplantation with Vitamin D Therapy Mitigates Paraspinal Muscle Atrophy and Neuropathic Pain Following Spinal Surgery

Chronic pain after spinal surgery (CPSS) is frequently accompanied by paraspinal muscle atrophy (PMA). This study aimed to explore the potential of mitochondrial transplantation and/or vitamin D (VitD) therapy to counteract PMA- and pain-associated mitochondrial dysfunction. Plasma-derived mitochondria (pMT) were collected from human blood samples. The structure, size, and purity of the pMT were verified, and their mitochondrial respiratory enzyme activity was analyzed. A 2-week rat model of CPSS was created at the fifth left lumbar vertebra through denervation and laminectomy. The rats were assigned to 5 groups, namely, pMT/VitD, pMT, VitD, surgery, and control and administered intramuscular pMT ± VitD injections. The effects elicited in each group were investigated after 2 weeks via muscle morphology measurement and comprehensive tissue analysis. Combined pMT and VitD treatments showed potential in alleviating surgery-induced muscle atrophy and modulating pain responses. Thus, pMT and/or VitD treatment restored muscle atrophy by modulating proteostasis, suppressing apoptosis, and increasing PGC1α levels. Male Sprague Dawley rats (age, 12 weeks; weight, 340–370 g) were divided into five groups: pMT/VitD (pMT/VitD injection after surgery), pMT (pMT injection after surgery without VitD), VitD (VitD injection after surgery without pMT), surgery (no treatment after surgery), and control (no injury) groups. Total RNA was extracted from the multifidus muscles using the easy-spin total RNA extraction kit (iNtRON Biotechnology, Seoul, Republic of Korea).The Illumina sequencing NovaSeq platform (Illumina, San Diego, CA, USA) was used for generating paired-end sequencing reads. The reads were prepared for analysis using the Trimmomatic version 0.38 to remove adapter sequences and trim the low-quality bases. Subsequently, the processed reads were aligned to the Rattus norvegicus reference genome (rn6) using HISAT version 2.1.0 by incorporating both HISAT and Bowtie2 for alignment. Reference genome sequences and gene annotation data were sourced from the NCBI Genome Assembly and NCBI RefSeq databases.