Decompression Using Minimally Invasive Surgery for Lumbar Spinal Stenosis Associated with Degenerative Spondylolisthesis: A Review.

Lumbar spinal stenosis (LSS), which often occurs concurrently with degenerative spondylolisthesis (DS), is a common disease in the elderly population, affecting the quality of life of aged people significantly. Notwithstanding the frequently good effect of conservative therapy on LSS, a minority of the patients ultimately require surgery. Surgery for LSS aims to decompress the narrowed spinal canals with preservation of spinal stability. Traditional open surgery, either pure decompression or decompression with fusion, was considered effective for the treatment of LSS with or without DS. However, the long-term clinical outcomes of traditional open surgery are still unclear. Moreover, the disadvantages of conventional open surgery are extensive, examples including tissue injuries or secondary instability, with limited outcomes and significant reoperation rates. With the development and improvement of surgical tools, various minimally invasive spine surgery (MISS) methods, including indirect decompression techniques of interspinous process devices (IPDs) and direct decompression techniques such as microscopic spine surgery or endoscopic spine surgery (ESS), have been updated with enhancement. IPDs, such as Superion devices, were reported to behave with comparable physical function, disability, and symptoms outcomes to laminectomy decompression. As an emerging technique of MISS, ESS has beneficial hallmarks including minimal tissue injuries, reduced complication rates, and shortened recovery periods, thus gaining popularity in recent years. ESS can be classified in terms of endoscopic hallmarks and approaches. Predictably, with the continuous development and gradual maturity, MISS is expected to replace traditional open surgery widely in the surgical treatment of LSS associated with DS in the future.

Landscape of RNAs in human lumbar disc degeneration.

Accumulating evidence indicates noncoding RNAs (ncRNAs) fine-tune gene expression with mysterious machinery. We conducted a combination of mRNA, miRNA, circRNA, LncRNA microarray analyses on 10 adults' lumbar discs. Moreover, we performed additional global exploration on RNA interacting machinery in terms of in silico computational pipeline. Here we show the landscape of RNAs in human lumbar discs. In general, the RNA-abundant landscape comprises 14,635 mRNAs (37.93%), 2,059 miRNAs (5.34%), 18,995 LncRNAs (49.23%) and 2,894 (7.5%) circRNAs. Chromosome 1 contributes for RNA transcription at most (10%). Bi-directional transcription contributes evenly for RNA biogenesis, in terms of 5' to 3' and 3' to 5'. Despite the majority of circRNAs are exonic, antisense (1.49%), intergenic (0.035%), intragenic (1.69%), and intronic (6.29%) circRNAs should not be ignored. A single miRNA could interact with a multitude of circRNAs. Notably, CDR1as or ciRS-7 harbors 66 consecutive binding sites for miR-7-5p (previous miR-7), evidencing our pipeline. The majority of binding sites are perfect-matched (78.95%). Collectively, global landscape of RNAs sheds novel insights on RNA interacting mechanisms in human intervertebral disc degeneration.

FasL on human nucleus pulposus cells prevents angiogenesis in the disc by inducing Fas-mediated apoptosis of vascular endothelial cells.

The intervertebral disc is the largest avascular organ in the human body. However, with the progress of intervertebral disc degeneration (IDD), the disc tends to be vascularized increasingly via angiogenesis. It is well established that both human nucleus pulposus (NP) cells and vascular endothelial cells express FasL and Fas. However, the issue remains open as to whether there are certain active mechanisms preventing angiogenesis in the disc via the FasL-Fas machinery. Here, we established a co-culture system of human NP cells and vascular endothelial (HMEC-1) cells. We found that normal NP cells were more capable of inducing apoptosis in HMEC-1 cells (14.2±3.4%) than degenerate NP cells (6.7±1.9%), p<0.05. By up-regulating the FasL expression in degenerate NP cells, we found that FasL played an essential role in the mediation of HMEC-1 cell apoptosis with the activation of downstream FADD and caspase-3. Furthermore, we found an increased Fas expression in HMEC-1 cells following co-cultured with NP cells, which might be closely linked with FasL produced by NP cells and enhance their interaction. Collectively, this is the first study showing FasL-Fas network might plays an important role in the molecular mechanisms of angiogenesis avoidance of human disc. Consequently, our findings might shed light on the pathogenesis in human IDD and provide a novel target for the treatment strategies for IDD.

Expression of soluble Fas and soluble FasL in human nucleus pulposus cells.

The study aimed for addressing the expression of soluble Fas (sFas) and soluble Fas Ligand (sFasL) in human nucleus pulposus (NP) and its attendant relationship with disc degeneration. Human NP samples were collected from patients with disc degeneration and cadavers as degenerate and normal groups, respectively. Subsequently, NP cells were cultured in monolayer. ELISA was performed to identify the expression levels of sFas and sFasL in the supernatant of NP cell cultures in vitro. Quantitative real-time PCR was used to detect the expression of sFas and sFasL in human NP cells in mRNA solution. The study comprised 12 degenerate and 8 normal cadaveric NP samples. The concentration value of sFas in the supernatant was significantly higher from degenerate NP than that from normal NP at each time point. In contrast, sFasL was significantly lower at each time point. Moreover, the expression of sFas and sFasL reached the peak at various early stages of cell cultures and decreased thereafter. Furthermore, the mRNA level of Fas in degenerate NP cells was significantly higher than that in normal cells; whereas FasL showed an opposite pattern. The study is the first addressing the expression of sFas and sFasL in human NP cell cultures. Moreover, the expression of sFas and sFasL varies with culture time in vitro with different levels in degenerate and normal settings. These findings indicate that sFas and sFasL might play a role in intervertebral disc degeneration.

Molecular immunotherapy might shed a light on the treatment strategies for disc degeneration and herniation.

Despite surgical discectomy is one of the most effective treatments for intervertebral disc degeneration and lumbar disc herniation, a number of patients still complain of reserved low back pain, sciatica and numbness post-operatively with decreased life quality. Sciatica in patients with disc herniation is not only due to mechanical compression from herniated nucleus pulposus, but chemical and immunity agents. The intervertebral disc is composed of annulus fibrosus in the wedge and gelatinous nucleus pulposus in the centre with cartilage endplate sandwiched. Similar to other immune privilege organs, human intervertebral disc is one of the biggest avascular structures with FasL expression. Moreover, FasL-Fas and TRAIL death pathways might play roles in the machinery of immune privilege of the disc. We found that down-regulated miR-155 promotes Fas-mediated apoptosis in disc degeneration. Furthermore, once exposed to human immune system, nucleus pulposus can activate multiple specific and non-specific immune responses with cellular and fluid immune cells and molecules involved. Taken together, we hypothesize that a combined molecular immunotherapy with local and systemic immunity regulators might shed a novel light on the treatment strategies for disc degeneration and herniation.