Efficiency of dual siRNA-mediated gene therapy for intervertebral disc degeneration (IVDD).

BACKGROUND CONTEXT: One of the common causes of low back pain is intervertebral disc degeneration. The pathophysiology of disc degeneration involves apoptosis of nucleus pulposes cells and degradation of extra cellular matrix (ECM). Caspase 3 plays a central role in apoptosis and the ADAMTS5 (A Disintegrin and Metalloproteinase with Thrombospondin motifs 5) gene plays a critical role in ECM degradation. Hence, we hypothesized that if one can silence these two genes, both apoptosis and ECM degradation can be prevented, thereby preventing the progression and even reverse disc degeneration. PURPOSE: The purpose of this study is to demonstrate the regenerative potential of small interfering RNA (siRNA) designed against Caspase 3 and ADAMTS5 genes in an in vitro and animal model of disc degeneration. STUDY DESIGN: In vitro study followed by in vivo study in a rabbit model. METHODS: In vitro studies were done using the human hepatocellular carcinoma (Hep G2) cell line for validating the efficacy of liposomal siRNA in controlling the expression of genes (Caspase 3 and ADAMTS5). Later, siRNA's validation was done in a rabbit annular punctured model by administering siRNA's individually (Caspase 3 and ADAMTS5) and in combination Caspase3-ADAMTS5) for assessing their synergistic effect in down regulating the gene expression in the degenerative discs. Annular punctured intervertebral discs of the rabbit were injected with siRNA formulations (single and dual) and phosphate buffer saline, one week after initial puncture. Magnetic resonance imaging (MRI) scans were done before and after siRNA treatment (1, 4 and 8 weeks) for assessing the progression of disc degeneration. The histopathology and real time polymerase chain reaction (RT-PCR) studies were done for evaluating their efficacy. We did not receive any funding for conducting the study, and we do not have a conflict of interest with any researchers or scientific groups. RESULTS: The observations made from both in vitro and in vivo studies indicate the beneficial effects of siRNA formulation in down regulating the expression of Caspase 3 and ADAMTS5 genes. The MRI and histopathological evaluation showed that the disc degeneration was progressive in phosphate buffer saline and AT5-siRNA injected discs but the discs that received Caspase 3-siRNA and dual siRNA (Cas3-AT5-siRNA) formulation showed signs of recovery and regeneration 4 and 8 weeks after injection. The efficacy of siRNA designed against Cas3 and AT5 was also assessed in both in vitro and in vivo experiments by using RT-PCR analysis and the results showed downregulation of Caspase 3 gene in Caspase 3-siRNA group, but there was no significant downregulation of ADAMTS5 gene in ADAMTS5-siRNA group (ie, indicated by fold change). Synergistic effect was observed in the group that received dual siRNA (Cas3-AT5 siRNA) formulation. CONCLUSIONS: This experiment suggests that intervention by siRNA treatment significantly reduced the extent of apoptosis in the discs. CLINICAL SIGNIFICANCE: Delivery of siRNA directly into spinal discs has a potential in treating disc degeneration nonsurgically.

Development of Novel Animal Model for Studying Scoliosis Using a Noninvasive Method and Its Validation through Gene-Expression Analysis.

STUDY DESIGN: To induce scoliosis in young female Wistar rats using a noninvasive method and to validate this model. PURPOSE: To induce scoliosis in a rat model noninvasively by bracing and to study the corresponding gene-expression profile in the spine and different organs. OVERVIEW OF LITERATURE: Scoliosis involves abnormal lateral curvature of the spine, the causes of which remain unclear. In the literature, it is suggested that scoliosis is genetically heterogeneous, as there are multiple factors involved directly or indirectly in its pathogenesis. Clinical and experimental studies were conducted to understand the etiology of anatomical alterations in the spine and internal organs, as the findings could help clinicians to establish new treatment approaches. METHODS: Twelve female Wistar rats aged 21 days were chosen for this study. Customized braces and real-time polymerase chain reaction (RT-PCR) primers for rats were designed using Primer 3 software. Radiological analysis (X-rays), histopathological studies, SYBR green, and RT-PCR analysis were performed. RESULTS: The spines of six rats were braced in a deformed position, which resulted in a permanent structural deformity as confirmed by X-ray studies. The remaining rats were used as controls. Quantitative studies of the expression of various genes (osteocalcin, pleiotrophins, matrix metalloproteinase-2 [MMP2] and MMP9, TIMP, interleukins 1 and 6, tumor necrosis factor-α) showed their differential expression and significant upregulation (p<0.05) in different organs of scoliotic rats in comparison to those in control rats. Histopathological findings showed tissue necrosis and fibrosis in the brain, retina, pancreas, kidney, liver, and disc of scoliotic rats. CONCLUSIONS: Bracing is a noninvasive method for inducing scoliosis in an animal model with 100% reliability and with corresponding changes in gene expression. Scoliosis does not just involve a spine deformity, but can be referred to as a systemic disease on the basis of the pathological changes observed in various internal organs.

Enchondroma Protuberans of the Transverse Process of D8 Vertebra Extending to the 7th and 8th Ribs: A Rare Case Report.

BACKGROUND: Enchondroma protuberans (EP) is rare, benign cartilaginous bone tumor arising from the intramedullary cavity of long bones and usually protrudes beyond the cortex with an exophytic growth pattern resembling osteochondroma. This study reports on a rare case of EP arising from the transverse process of the D8 vertebra and extending to the adjacent 7th and 8th ribs and the paraspinal tissues. METHODS: A 45-year-old female patient came in with complaints of upper back pain radiating up to the left costal margin for the past 6 months. There were no parasthesias, and there was no history of any sensory or motor symptoms. On physical examination there was midline and left paraspinal tenderness over the D6 to D8 region. Anteroposterior and lateral X-ray images revealed a well-defined oval ossific mass lesion over the lateral aspect of the D8 vertebra, extending to the 7th and 8th ribs on the left side, and multiple bridging osteophytes were noted. Computed tomography scan showed an ossific mass lesion arising from the D8 transverse process with extension to the adjacent 7th and 8th ribs; its margins were well defined, with no periosteal reaction. Magnetic resonance imaging showed a well-defined expansile mass lesion arising from the transverse process of the D8 vertebra matrix; it was was isointense with adjacent marrow and had no evidence of calcifications or vascular flow voids and no encroachment into the spinal canal. RESULTS: Complete resection of the mass lesion with the adjacent part of the 7th and 8th ribs and with intramedullary curettage was performed and sent for histopathologic examination. Histopathology showed bony trabeculae with normal mucosal elements, and a mild hypercellularity with binucleation. Chondrocytes in the myxoid matrix located in round lacunae were compatible with enchondroma, with no evidence of atypia. The postoperative period was uneventful, and after 12 months there were no signs of recurrence noted in computed tomography scan. CONCLUSIONS: EP is a rare presentation in the dorsal spine; it should be considered in the differential diagnosis of osteochondroma, enchondroma, chondrosarcoma, and periosteal chondroid tumors.