Therapeutic CRISPR epigenome editing of inflammatory receptors in the intervertebral disc.

Low back pain (LBP) ranks among the leading causes of disability worldwide and generates a tremendous socioeconomic cost. Disc degeneration, a leading contributor to LBP, can be characterized by the breakdown of the extracellular matrix of the intervertebral disc (IVD), disc height loss, and inflammation. The inflammatory cytokine tumor necrosis factor α (TNF-α) has multiple signaling pathways, including proinflammatory signaling through tumor necrosis factor receptor 1 superfamily, member 1a (TNFR1 or TNFRSF1A), and has been implicated as a primary mediator of disc degeneration. We tested our ability to regulate the TNFR1 signaling pathway in vivo, utilizing CRISPR epigenome editing to slow the progression of disc degeneration in rats. Sprague-Dawley rats were treated with TNF-α and CRISPR interference (CRISPRi)-based epigenome-editing therapeutics targeting TNFR1, showing decreased behavioral pain in a disc degeneration model. Surprisingly, while treatment with the vectors alone was therapeutic, the TNF-α injection became therapeutic after TNFR1 modulation. These results suggest direct inflammatory receptor modulation as a potent strategy for treating disc degeneration.

Multiplex gene editing to promote cell survival using low-pH clustered regularly interspaced short palindromic repeats activation (CRISPRa) gene perturbation.

BACKGROUND AIMS: Lower back pain is the leading cause of disability worldwide and is often linked to degenerative disc disease (DDD), the breakdown of intervertebral discs. The majority of treatment options for DDD are palliative, with clinicians prescribing medication or physical therapy to return the patient to work. Cell therapies are promising treatment options with the potential to restore functional physiological tissue and treat the underlying causes of DDD. DDD is characterized by biochemical changes in the microenvironment of the disc, including changes in nutrient levels, hypoxia, and changes in pH. Stem cell therapies are promising therapies to treat DDD, but the acidic environment in a degenerating disc significantly hinders the viability of stem cells, affecting their efficacy. Clustered regularly interspaced short palindromic repeats (CRISPR) systems allow us to engineer cell phenotypes in a well-regulated and controlled manner. Recently, CRISPR gene perturbation screens have assessed fitness, growth and provided a means for specific cell phenotype characterization. METHODS: In this study, we use a CRISPR-activation (a) gene perturbation screen to identify gene upregulation targets that enhance adipose-derived stem cell survival in acidic culture conditions. RESULTS: We identified 1213 prospective pro-survival genes and systematically narrowed these down to 20 genes for validation. We further narrowed down our selection to the top five prospective genes using Cell Counting Kit-8 cell viability assays in naïve adipose-derived stem cells and ACAN/Col2 CRISPRa upregulated stem cells. Finally, we examined the extracellular matrix-producing abilities of multiplex ACAN/Col2-pro-survival edited cells in pellet culture. CONCLUSIONS: Using the results from the CRISPRa screen, we are able to engineer desirable cell phenotypes to improve cell viability for the potential treatment of DDD and other disease states that expose cell therapies to acidic environments, while also providing broader knowledge on genes regulating low-pH cell survival.

The Relationship of PROMIS Pain Interference and Physical Function Scales.

Objectives: To examine the relationship between the Patient Reported Outcome Measurement Information System (PROMIS) Pain Interference (PI) and PROMIS Physical Function (PF) scales in patients with spinal pain at a university spine center. Design: Retrospective analysis of prospectively collected patient-reported outcome data at a university spine clinic. Pearson correlation was done to examine the relationship of the PROMIS PF and PROMIS PI scores. Age, gender, and race were analyzed by subgroups on the PROMIS Physical Function and Pain Interference score. Linear regression analyzed predictive relationships. Statistical significance was set at P < 0.05. Results: A total of 1,992 participants completed an assessment, with 1,923 completing the PF CAT and 1,927 the PI CAT. Participants' mean age was 52.8 years (range = 18-94 years, SD = 6.5 years). Correlation analysis of the PROMIS PF with the PROMIS PI showed a Pearson correlation value of -0.717 (P < 0.05). There was a strong linear relationship with a high negative correlation between PF CAT and PI CAT. The PI CAT predicted PF CAT scores (ß = -0.707, P < 0.001). Conclusions: For patients with pain from spinal origin, there is a strong negative correlation between self-reported physical function and pain interference related to physical, social, and mental health. The predictive relationship of function from pain scores supports the PROMIS PI being used as an important adjunct measure of physical function in patients with spinal pain.

CRISPR Epigenome Editing of AKAP150 in DRG Neurons Abolishes Degenerative IVD-Induced Neuronal Activation.

Back pain is a major contributor to disability and has significant socioeconomic impacts worldwide. The degenerative intervertebral disc (IVD) has been hypothesized to contribute to back pain, but a better understanding of the interactions between the degenerative IVD and nociceptive neurons innervating the disc and treatment strategies that directly target these interactions is needed to improve our understanding and treatment of back pain. We investigated degenerative IVD-induced changes to dorsal root ganglion (DRG) neuron activity and utilized CRISPR epigenome editing as a neuromodulation strategy. By exposing DRG neurons to degenerative IVD-conditioned media under both normal and pathological IVD pH levels, we demonstrate that degenerative IVDs trigger interleukin (IL)-6-induced increases in neuron activity to thermal stimuli, which is directly mediated by AKAP and enhanced by acidic pH. Utilizing this novel information on AKAP-mediated increases in nociceptive neuron activity, we developed lentiviral CRISPR epigenome editing vectors that modulate endogenous expression of AKAP150 by targeted promoter histone methylation. When delivered to DRG neurons, these epigenome-modifying vectors abolished degenerative IVD-induced DRG-elevated neuron activity while preserving non-pathologic neuron activity. This work elucidates the potential for CRISPR epigenome editing as a targeted gene-based pain neuromodulation strategy.

What Are the MCIDs for PROMIS, NDI, and ODI Instruments Among Patients With Spinal Conditions?

BACKGROUND: As new Patient-Reported Outcomes Measurement Information System (PROMIS) instruments are incorporated into clinical practice, determining how large a change on these instruments represents a clinically relevant difference is important; the metric that describes this is the minimum clinically important difference (MCID). Prior research on MCIDs of the Neck Disability Index (NDI) and Oswestry Disability Index (ODI) has produced values ranging from 5 to 10 points, but these measures have not been presented in relation to MCID values of PROMIS instruments. QUESTIONS/PURPOSES: To establish a comprehensive repository of MCID values calculated both with distribution-based and anchor-based methods for four outcomes instruments in spine care, we asked: (1) What are the MCIDs of the PROMIS Physical Function (PF); (2) the PROMIS Pain Interference (PI); (3) the NDI; and (4) the ODI among spine patients? METHODS: We conducted a prospective study of previously tested diagnostic measures on 1945 consecutive patients with a reference standard applied. All patients aged 18 years and older visiting an orthopaedic spine clinic between October 2013 and January 2017 completed the PROMIS PF and PI, NDI, and ODI on tablet computers before their clinic visits. Patients were grouped by change level (self-report of meaningful change versus slight or no change) using an anchor question in comparison to baseline. Descriptive statistics, two anchor-based MCID values (mean change and receiver operating characteristic curve), and five distribution-based values (SD at 1/2 and 1/3 values and minimum detectable change [MDC] at 90%, 95%, and 99%) were analyzed four different times between 3 months and > 6 months of followup. A total of 1945 included patients with a wide range of spine conditions and varying treatments had a mean age of 58 years (SD = 15.5), were 51% (988 of 1945) male, 90% (1754 of 1945) self-identified as white, and 5% (94 of 1945) as Hispanic with 1% to 2% of patients refusing participation. RESULTS: The PROMIS PF mean change scores in the changed group (much worse, worse, improved, or much improved) ranged between 7 and 8 points. MCID values ranged from 3 to 23 points depending on the method of calculation with a median of 8. For the PROMIS PI, mean change scores ranged from 8 to 9 points and MCID values from 1 to 24 points with a median of 8. For the NDI, mean change scores ranged from 13 to 18 points and MCID values ranged from 6 to 43 points with a median of 18. For the ODI, mean change ranged from 17 to 19 points and MCID values ranged from 7 to 51 points with a median of 24. For each instrument, distribution-based SD yielded the smallest values, followed by anchor-based methods, with MDC yielding the largest MCID values. CONCLUSIONS: This study uses a range of methods for determining MCIDs of the PROMIS PF and PI, NDI, and ODI from anchor-based to distribution-based methods. MCIDs do not have a static value for a given outcome measure, but have a range of values and are dependent on the method calculated. The lowest MCIDs identified for the NDI and ODI are consistent with prior studies, but those at the upper range are much higher. Anchor-based methods are thought to be most relevant in the clinical setting and are more easily understood by clinicians, whereas the distribution-based MCIDs are useful in understanding population breadth. Lower MCID values may be most appropriate for screening purposes or low-risk effects, and the median or higher MCID values should be used for high-risk effects or outcomes. LEVEL OF EVIDENCE: Level I, diagnostic study.

The effect of aging on posterior intertransverse lumbar fusion: a New Zealand white rabbit model.

STUDY DESIGN: In vivo assessment of lumbar spinal fusion between a younger and older cohort of New Zealand white rabbits. OBJECTIVE: Directly compare fusion within young and aged New Zealand white rabbits to establish an aged spinal fusion model translational research. SUMMARY OF BACKGROUND DATA: Prior studies have utilized skeletally mature young rabbits (6-12 mo old) that may not be appropriate as an analog for studying the aging human spine. METHODS: Ten aged (>36 mo old) and 10 young (12 mo old) New Zealand white rabbits underwent a single-level, bilateral, L5-6 posterolateral intertransverse fusion using autogenous iliac crest bone graft. The animals were killed at 6 weeks postoperatively, and the specimens were then evaluated with quantitative microcomputerized tomography and manual palpation by 6 orthopedic surgeons. The fusions were graded as either fused or not fused by each examiner. The spines were then embedded in poly(methyl methacrylate) and cut into 2-mm-thick sections for histologic analysis. RESULTS: A higher percentage of young rabbits were determined to be successfully fused through manual palpation testing compared with the aged rabbits. Micro-computed tomography (CT) analysis revealed a significantly greater fusion mass volume in the younger rabbits than in the older cohort. In addition, the fusion density of the younger rabbits was found to be significantly lower than that of the older rabbits when normalized to the bone density in the nonfused portion of the spine. Histologic analysis showed that the quality of the bone within the fusion mass was consistent between the young and old rabbits. A greater number of young animals had bilateral continuous bone graft compared with the aged animals. CONCLUSIONS: The aged (>36 mo) New Zealand white rabbit model appears to be a valid model to evaluate the effect of aging on lumbar fusion and has the potential to more accurately model conditions that are present in the older human spine.

Measuring the impact of the Thoracolumbar Injury Classification and Severity Score among 458 consecutively treated patients.

CONTEXT: The Thoracolumbar Injury Classification and Severity Score (TLICS) was proposed to improve injury classification and guide surgical decision-making of thoracolumbar spinal trauma (TLST), but its impact on the care of patients has not been quantified. STUDY DESIGN: Retrospective study. PATIENT SAMPLE: Analysis of 458 patients treated for TLST trauma from 2000 through 2010 at a single center. Outcome measures Neurological status - ASIA Impairment Scale (AIS), failure of conservative treatment, and surgical complications. METHODS: Clinical and radiological data were evaluated. Patients were grouped according to the period before (2000-2006) and after (2007-2010) utilization of the TLICS. RESULTS: From 2000 to 2006, 148 patients were initially treated conservatively (C) and 66 were surgically (S) treated. In the C group, the TLICS ranged from 1 to 7 (median 1; mean 1.57). In the S group, the TLICS ranged from 2 to 10 (median 2; mean 4.14). The TLICS matched treatment in 97.9% of conservatively treated patients. From 2007 to 2010, 162 patients were initially treated C and 82 were treated S. In the C group, the TLICS ranged from 1 to 4 (median 1; mean 1.48). In the S group, the TLICS ranged from 2-10 (median 4; mean 4.4). The TLICS matched treatment in 98.8% of C-treated patients. Overall, failure of C treatment occurred in nine patients; most failures (7/9) and all three missed distractive injuries occurred prior to use of the TLICS. CONCLUSIONS: After introduction of the TLICS, there was a trend towards more successful conservative treatment with fewer conversions to surgical treatment.

Upper cervical injuries - a rational approach to guide surgical management.

CONTEXT: The complex anatomy and the importance of ligaments in providing stability at the upper cervical spine region (O-C1-C2) require the use of many imaging modalities to evaluate upper cervical injuries (UCI). While separate classifications have been developed for distinct injuries, a more practical treatment algorithm can be derived from the injury pattern in UCI. OBJECTIVE: To propose a practical treatment algorithm to guide treatment based on injuries characteristic of UCI. METHODS: A literature review was performed on the Pubmed database using the following keywords: (1) "occipital condyle injury"; (2) "craniocervical dislocation or atlanto-occipital dislocation or craniocervical dislocation"; (3) "atlas fractures"; and (4) "axis fractures". Just articles containing the diagnosis, classification, and treatment of specific UCI were included. The data obtained were analyzed by the authors, dividing the UCI into two groups: Group 1 - patients with clear ligamentous injury and Group 2 - patients with fractures without ligament disruption. RESULTS: Injuries with ligamentous disruption, suggesting surgical treatment, include: atlanto-occipital dislocation, mid-substance transverse ligament injury, and C1-2 and C2-3 ligamentous injuries. In contrast, condyle, atlas, and axis fractures without significant displacement/misalignment can be initially treated using external orthoses. Odontoid fractures with risk factors for non-union are an exception in Group 2 once they are better treated surgically. Patients with neurological deficits may have more unstable injuries. CONCLUSIONS: Ascertaining the status of relevant ligamentous structures, fracture patterns and alignment are important in determining surgical compared with non-surgical treatment for patients with UCI.

Hangman's Fractures: A Review of Current Concepts in Evaluation and Management.

STUDY DESIGN: Review article. OBJECTIVE: To provide a comprehensive review and update on the evaluation and management of Hangman's fractures. SUMMARY OF BACKGROUND DATA: Hangman's fractures are the second most common fracture of the C2 vertebrae, and the prevalence is increasing with our aging population. Although these injuries are associated with good clinical outcomes and low rates of neurologic injury, they must be promptly recognized and treated according to patient and fracture factors. METHODS: A review of the literature. RESULTS: Neurologic injuries are uncommon in typical Hangman's fractures but are more of a concern in atypical Hangman's fractures due to lack of dissociation of the posterior ring of C2. The nonoperative treatment of stable type I, II, and atypical fractures with external immobilization leads to excellent long-term outcomes as does the operative treatment of unstable type IIa, III, and atypical fractures. CONCLUSIONS: Stable injury patterns can be treated with immobilization alone, whereas unstable injury patterns necessitate surgical treatment. Prompt diagnosis and treatment Hangman's fractures is paramount, and when managed properly, patients can have excellent clinical and neurologic outcomes.

Toward the Development of a Tissue Engineered Gradient Utilizing CRISPR-Guided Gene Modulation.

Cellular, compositional, and mechanical gradients are found throughout biological tissues, especially in transition zones between tissue types. Yet, strategies to engineer such gradients have proven difficult due to the complex nature of these tissues. Current strategies for tissue engineering complex gradients often utilize stem cells; however, these multipotent cells require direction from environmental cues, which can be difficult to control both in vitro and in vivo. In this study, we utilize clustered regularly-interspaced short palindromic repeats (CRISPR)-guided gene modulation to direct the differentiation of multipotent adipose-derived stem cells (ASCs) to demonstrate the effectiveness of CRISPR-engineered cells in tissue engineering applications. Specifically, we screen CRISPR-interference (CRISPRi) constructs targeting the promotors of selected osteogenic inhibitors and demonstrate that ASC osteogenic differentiation and mineral deposition can be regulated with CRISPRi targeting of Noggin without the use of exogenous growth factors in tissue engineered constructs. As a proof of concept, we combine three technologies developed out of our laboratories to demonstrate the controlled deposition of these engineered cells in a gradient with CRISPR-activation multiplex-engineered aggrecan/collagen type-II-chondrogenic ASCs on a high density anisotropic type I collagen construct to create a cell and tissue gradient similar to the fibrocartilage-to-mineralized-fibrocartilage gradient in the enthesis. Our results display the promise of CRISPR-engineered ASCs to produce tissue gradients, similar to what is observed in native tissue.

How Do Functional Comorbidities Affect PROMIS-PF Scores Following Lumbar Fusion Surgery?

STUDY DESIGN: A retrospective review. OBJECTIVE: The purpose of this study is to trend PROMIS PF scores following lumbar fusion surgery, and to investigate how the presence of functional comorbidities affects PROMIS PF scores. Additionally, we compare trends in PROMIS PF scores to the Oswestry Disability Index (ODI) and to PROMIS Pain Interference (PI) scores. SUMMARY OF BACKGROUND DATA: National Institute of Health's (NIH) Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF) domain has been validated in spine surgery. However, little is known about how PROMIS-PF scores are affected by functional comorbidities and how these scores change in patients recovering from lumbar fusion surgery over time. In this study, we hypothesize that functional comorbidities negatively affect recovery. METHODS: We retrospectively identified 1,893 patients who underwent thoracolumbar, lumbar, or lumbosacral fusion for degenerative conditions between 01/02/2014 and 01/07/2022. We summarized PF at 3-month intervals for 2 years following surgery between those with and without functional comorbidity, defined as the presence of congestive heart failure (HF), chronic obstructive pulmonary disease (COPD), cerebrovascular disease (CVD), or paraplegia. Mixed effects multivariable regressions were used to model between group trends in PF through 2 years post-operatively controlling for age, gender, indication, and surgical invasiveness. The minimally clinically important difference (MCID) was defined as 5+ point improvement from baseline in PF. RESULTS: The cohort includes 1,224 (65%) patients without functional comorbidity and 669 (35%) with functional comorbidity. The mean age was 65.0 and Charlson index was 1.0 in the cohort without functional comorbidity compared to 65.4 and 3.8 in the cohort with functional comorbidity (P=0.552 and P<0.001 respectively). The groups were otherwise similar with respect to surgical invasiveness index, vertebral levels, and spine diagnosis (all P>0.05). At 24 months post operatively, the functional comorbidity group had a 2.5 point lower absolute PF score and a 1.3 point less improvement from baseline (P=0.012 and 0.190 respectively). 19.3% of patients in the functional comorbidity group achieved the MCID compared to 80.9% in patients without a functional comorbidity (P<0.001). CONCLUSION: Based on PROMIS PF scores, patients with functional comorbidities do not recover to the same extent and are less likely to achieve an MCID compared to patients without baseline functional comorbidities. PROMIS-PF can help benchmark patients along their recovery, and other metrics may be needed to better understand the recovery of patients with functional comorbidities.

Transthyretin amyloidosis in spinal canal stenosis: A systematic review.

We systematically review literature regarding the contribution of transthyretin amyloidosis to spinal stenosis. Amyloidosis is a protein misfolding condition that causes systemic deposition of amyloid and commonly leads to heart failure and nephropathy. A growing body of literature suggests that amyloid deposits within the ligamentum flavum are frequently associated with spinal stenosis with subsequent myelopathy. Our search identified 67 publications from the PubMed database for literature review. After evaluating the inclusion and exclusion criteria, a total of 18 articles were included in the review. Each article was evaluated for country, study type, sample size, amyloidosis subtype, spinal level, systemic symptoms, treatment, patient outcome, and conclusions. Many studies concluded that lumbar ligamentum flavum hypertrophy is more severe in patients with amyloidosis due to associated amyloid deposition. Additionally, patients with systemic amyloidosis are more likely to have recurrence of spinal stenosis. Multiple studies encourage routine screening be performed on spinal stenosis patients to target those needing cardiac surveillance. Amyloid deposition is frequently associated with spinal stenosis, and its presence may provide an earlier opportunity to diagnose or predict systemic amyloidosis. Surgeons should consider obtaining intraoperative biopsy to identify amyloidosis and inform screening postoperatively. Finally, physicians should be aware of this association and counsel patients accordingly on the risks and treatment options available for amyloidosis.

The effect of lumbar medial branch radiofrequency neurotomy on cobb angle progression in individuals with adult scoliosis compared to natural history: A cross-sectional study.

Background: Lumbar radiofrequency neurotomy (LRFN) effectively alleviates zygapophyseal joint-mediated pain by coagulating medial branch nerves to disrupt nociceptive signaling pathways. The concomitant denervation of multifidus fibers has led to concern that LRFN may increase segmental instability and accelerate degenerative changes in patients with certain pre-existing spinal pathologies. There is a paucity of literature evaluating whether LRFN increases the progression of spinal curvature in patients with adult scoliosis. Objective: Compare the lumbosacral Cobb angle progression rate in patients with adult scoliosis who underwent LRFN to the annual progression rate of 0.83 ± 1.1° expected by natural history. Design: Cross-sectional study. Methods: Consecutive patients diagnosed with adult scoliosis who underwent LRFN to treat zygapophyseal joint-related low back pain were identified. Patient demographics, LRFN procedure details, and radiographs confirming scoliosis were collected from electronic medical records. Pre- and post-LRFN radiographs were used to calculate the average annual rate of Cobb angle progression. Data were analyzed using a Wilcoxon signed-rank test and a linear regression model. Results: Sixty patients (mean age 69.2 ± 11.6 years; 70.0 % female) met the criteria and were included in the analyses. The mean time to radiographic follow-up was 35.0 ± 22.7 months post-LRFN. The average Cobb angle progression was 0.54 ± 3.03° per year and did not differ significantly from the known natural progression rate of 0.83 ± 1.1° per year. None of the included covariates (body mass index, LRFN laterality, and number of levels denervated) were significantly associated with the average annual Cobb angle progression rate. Conclusions: Our results suggest that LRFN has no appreciable effect on the rate of Cobb angle progression in patients with adult scoliosis.

Factors Related to Clinical Performance in Spine Surgery Fellowship: Can We Predict Success.

INTRODUCTION: The factors most important in the spine fellowship match may not ultimately correlate with quality of performance during fellowship. This study examined the spine fellow applicant metrics correlated with high application rank compared with the metrics associated with the strongest clinical performance during fellowship. METHODS: Spine fellow applications at three academic institutions were retrieved from the San Francisco Match database (first available to 2021) and deidentified for application review. Application metrics pertaining to research, academics, education, extracurriculars, leadership, examinations, career interests, and letter of recommendations were extracted. Attending spine surgeons involved in spine fellow selection at their institutions were sent a survey to rank (1) fellow applicants based on their perceived candidacy and (2) the strength of performance of their previous fellows. Pearson correlation assessed the associations of application metrics with theoretical fellow rank and actual performance. RESULTS: A total of 37 spine fellow applications were included (Institution A: 15, Institution B: 12, Institution C: 10), rated by 14 spine surgeons (Institution A: 6, Institution B: 4, Institution C: 4). Theoretical fellow rank demonstrated a moderate positive association with overall research, residency program rank, recommendation writer H-index, US Medical Licensing Examination (USMLE) scores, and journal reviewer positions. Actual fellow performance demonstrated a moderate positive association with residency program rank, recommendation writer H-index, USMLE scores, and journal reviewer positions. Linear regressions identified journal reviewer positions (ß = 1.73, P = 0.002), Step 1 (ß = 0.09, P = 0.010) and Step 3 (ß = 0.10, P = 0.002) scores, recommendation writer H-index (ß = 0.06, P = 0.029, and ß = 0.07, P = 0.006), and overall research (ß = 0.01, P = 0.005) as predictors of theoretical rank. Recommendation writer H-index (ß = 0.21, P = 0.030) and Alpha Omega Alpha achievement (ß = 6.88, P = 0.021) predicted actual performance. CONCLUSION: Residency program reputation, USMLE scores, and a recommendation from an established spine surgeon were important in application review and performance during fellowship. Research productivity, although important during application review, was not predictive of fellow performance. LEVEL OF EVIDENCE: III. STUDY DESIGN: Cohort Study.

Multiplex epigenome editing of ion channel expression in nociceptive neurons abolished degenerative IVD-conditioned media-induced mechanical sensitivity.

Background: Low back pain is a major contributor to disability worldwide and generates a tremendous socioeconomic impact. The degenerative intervertebral disc (IVD) has been hypothesized to contribute to discogenic pain by sensitizing nociceptive neurons innervating the disc to stimuli that is nonpainful in healthy patients. Previously, we demonstrated the ability of degenerative IVDs to sensitize neurons to mechanical stimuli; however, elucidation of degenerative IVDs discogenic pain mechanisms is required to develop therapeutic strategies that directly target these mechanisms. Aims: In this study, we utilized CRISPR epigenome editing of nociceptive neurons to identify mechanisms of degenerative IVD-induced changes to mechanical nociception and demonstrated the ability of multiplex CRISPR epigenome editing of nociceptive neurons to modulate inflammation-induced mechanical nociception. Methods and Results: Utilizing an in vitro model, we demonstrated degenerative IVD-produced IL-6-induced increases in nociceptive neuron activity in response to mechanical stimuli, mediated by TRPA1, ASIC3, and Piezo2 ion channel activity. Once these ion channels were identified as mediators of degenerative IVD-induced mechanical nociception, we developed singleplex and multiplex CRISPR epigenome editing vectors that modulate endogenous expression of TRPA1, ASIC3, and Piezo2 via targeted gene promoter histone methylation. When delivered to nociceptive neurons, the multiplex CRISPR epigenome editing vectors abolished degenerative IVD-induced mechanical nociception while preserving nonpathologic neuron activity. Conclusion: This work demonstrates the potential of multiplex CRISPR epigenome editing as a highly targeted gene-based neuromodulation strategy for the treatment of discogenic pain, specifically; and, for the treatment of inflammatory chronic pain conditions, more broadly.

Hypoalbuminemia as a Predictor of Mortality, Disability, and Readmission in Patients Undergoing Spine Surgery: A Retrospective Analysis.

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVE: The objective of this study was to clarify the association between preoperative albumin status and mortality and morbidity in lumbar spine surgery. SUMMARY OF BACKGROUND DATA: Hypoalbuminemia is a known marker of inflammation and is associated with frailty. Hypoalbuminemia is an identified risk factor for mortality following spine surgery for metastases, yet has not been well studied among spine surgical cohorts outside of metastatic cancer. MATERIALS AND METHODS: We identified patients with preoperative serum albumin laboratory values who underwent lumbar spine surgery at a US public university health system between 2014 and 2021. Demographic, comorbidity, and mortality data were collected along with preoperative and postoperative Oswestry Disability Index (ODI) scores. Any cause readmission within 1 year of surgery was recorded. Hypoalbuminemia was defined as <3.5 g/dL in serum. We examined the Kaplan-Meier survival plots based on serum albumin. Multivariable regression models were used to identify the association between preoperative hypoalbuminemia with mortality, readmission, and ODI, while controlling for age, sex, race, ethnicity, procedure, and Charlson Comorbidity Index. RESULTS: Of 2573 patients, 79 were identified as hypoalbuminemic. Hypoalbuminemic patients had a significantly greater adjusted risk of mortality through 1 year (odds ratio=10.2; 95% CI: 3.1-33.5; P <0.001), and 7 years (hazard ratio=4.18; 95% CI: 2.29-7.65; P <0.001). Hypoalbuminemic patients had ODI scores 13.5 points higher (95% CI: 5.7-21.4; P <0.001) at baseline. Adjusted readmission rates were not different between groups through 1 year (odds ratio=1.15; 95% CI: 0.5-2.62; P =0.75) or through full surveillance (hazard ratio=0.82; 95% CI: 0.44-1.54; P =0.54). CONCLUSIONS: Preoperative hypoalbuminemia was strongly associated with postoperative mortality. Hypoalbuminemic patients did not have demonstrably worse outcomes in their functional disability beyond 6 months. Within the first 6 months following surgery, the hypoalbuminemic group improved at a similar rate to the normoalbuminemic group despite having a greater preoperative disability. However, causal inference is limited in this retrospective study.

Response to Preoperative Steroid Injections Predicts Surgical Outcomes in Patients Undergoing Fusion for Isthmic Spondylolisthesis.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The decision to pursue operative intervention for patients with isthmic spondylolisthesis is complex. Although steroid injections are a well-accepted therapeutic modality that may delay or obviate surgery, little is known regarding their ability to predict surgical outcomes. SUMMARY OF BACKGROUND DATA: Here, we examine whether improvement after preoperative steroid injections can accurately predict clinical outcomes after surgery. METHODS: A retrospective cohort analysis was performed on adult patients undergoing primary posterolateral lumbar fusion for isthmic spondylolisthesis between 2013 and 2021. Data were stratified into a control (no preoperative injection) group and an injection group (received a preoperative diagnostic and therapeutic injection). We collected demographic data, peri-injection visual analog pain scores (VAS) pain scores, PROMIS pain interference and physical function scores, Oswestry Disability Index, and VAS pain (back and leg). Student t test was utilized to compare baseline group characteristics. Linear regression was performed comparing changes in peri-injection VAS pain scores and postoperative measures. RESULTS: Seventy-three patients did not receive a preoperative injection and were included in the control group. Fifty-nine patients were included in the injection group. Of patients who received an injection, 73% had >50% relief of their preinjection VAS pain score. Linear regression revealed a positive interaction between the injection efficacy and postoperative pain relief as measured by VAS leg scores ( P <0.05). There was also an association between injection efficacy and back pain relief, though this did not achieve statistical significance ( P =0.068). No association was found between injection efficacy and improvement in Oswestry Disability Index or PROMIS measures. CONCLUSIONS: Steroid injections are often utilized in the nonoperative therapeutic management of patients with lumbar spine disease. Here, we demonstrate the diagnostic value of steroid injections in predicting postoperative leg pain relief in patients undergoing posterolateral fusion for isthmic spondylolisthesis.

Therapeutic TNF-alpha Delivery After CRISPR Receptor Modulation in the Intervertebral Disc.

Low back pain (LBP) ranks among the leading causes of disability worldwide and generates a tremendous socioeconomic cost. Disc degeneration, a leading contributor to LBP, can be characterized by the breakdown of the extracellular matrix of the intervertebral disc (IVD), disc height loss, and inflammation. The inflammatory cytokine TNF-α has multiple pathways and has been implicated as a primary mediator of disc degeneration. We tested our ability to regulate the multiple TNF-α inflammatory signaling pathways in vivo utilizing CRISPR receptor modulation to slow the progression of disc degeneration in rats. Sprague-Dawley rats were treated with CRISPRi-based epigenome-editing therapeutics targeting TNFR1 and showed a decrease in behavioral pain in a disc degeneration model. Surprisingly, while treatment with the vectors alone was therapeutic, TNF-α injection itself became therapeutic after TNFR1 modulation. These results suggest direct inflammatory receptor modulation, to harness beneficial inflammatory signaling pathways, as a potent strategy for treating disc degeneration.

Preoperative Fluoroscopically Guided Regional Erector Spinae Plane Blocks Reduce Opioid Use, Increase Mobilization, and Reduce Length of Stay Following Lumbar Spine Fusion.

STUDY DESIGN: Retrospective review. OBJECTIVE: To determine the effectiveness of erector spinae plane (ESP) blocks at improving perioperative pain control and function following lumbar spine fusions. METHODS: A retrospective analysis was performed on patients undergoing < 3 level posterolateral lumbar fusions. Data was stratified into a control group and a block group. We collected postop MED (morphine equivalent dosages), physical therapy ambulation, and length of stay. PROMIS pain interference (PI) and physical function (PF) scores, ODI, and VAS were collected preop and at the first postop visit. Chi-square and student's t-test (P = .05) were used for analysis. We also validated a novel fluoroscopic technique for ESP block delivery. RESULTS: There were 37 in the block group and 39 in the control group. There was no difference in preoperative opioid use (P = .22). On postop day 1, MED was reduced in the block group (32 vs 51, P < .05), and more patients in the block group did not utilize any opioids (22% vs 5%, P < .05). The block group ambulated further on postop day 1 (312 ft vs 204 ft, P < .05), and had reduced length of stay (2.4 vs 3.2 days, P < .05). The block group showed better PROMIS PI scores postoperatively (58 vs 63, P < .05). The novel delivery technique was validated and successful in targeting the correct level and plane. CONCLUSIONS: ESP blocks significantly reduced postop opioid use following lumbar fusion. Block patients ambulated further with PT, had reduced length of stay, and had improved PROMIS PI postoperatively. Validation of the block demonstrated the effectiveness of a novel fluoroscopic delivery technique. ESP blocks represent an underutilized method of reducing opioid consumption, improving postoperative mobilization and reducing length of stay following lumbar spine fusion.

Risk Factors for Postoperative Ileus in Patients Undergoing Spine Surgery.

STUDY DESIGN: Retrospective Cohort Study. OBJECTIVES: Postoperative ileus (POI) is a common complication following elective spinal surgeries. The aim of this study was to determine the incidence of POI and identify demographic and surgical risk factors for developing POI after elective instrumented fusion of the thoracolumbar spine. METHODS: The University of Utah Institutional Review Board (IRB) approved this retrospective study. The study does not require informed consent given the data reviewed was deidentified and collected in accordance with the institution's standard of care. A designated IRB committee determined that study is exempt under exemption category 7. IRB approval number 00069703. Patients undergoing instrumented thoracolumbar fusion for one or more levels were retrospectively identified from an internal spine surgery database. Cases performed for trauma, infection, or tumors were excluded. Demographics, medical comorbidities, surgical variables, and opioid medication administration (morphine milligram equivalents, MME) were abstracted from the electronic medical record. Univariate analysis was used to identify variables associated with POI. These variables were then tested for independent association with POI using multivariate logistic regression. RESULTS: 418 patients were included in the current study. The incidence of POI was 9.3% in this cohort. There was no significant relationship between development of POI and patient age, gender, BMI, diabetes mellitus, thyroid dysfunction, lung disease, CKD, GERD, smoking status, alcohol abuse, anemia, or prior abdominal surgery. Univariate analysis demonstrated significant association between POI and fusion ≥7 levels compared to fusions of fewer levels (P = .001), as well as intraoperative sufentanil compared to other opioids (35.9% vs 20.1%, P = .02). POI was not significantly associated with total intraoperative MME, approach, use of interbody cage, or osteotomy. Multivariate logistic regression confirmed total 24-hour postoperative MME as an independent risk factor for POI (OR 1.004, P = .04), however, intraoperative sufentanil administration was not an independent risk factor for POI when controlling for other variables. CONCLUSIONS: This retrospective cohort study demonstrates that greater postoperative MME is an independent risk factor for POI after thoracolumbar spine fusion when accounting for demographic, medical, and surgical variables with multiple logistic regression. Prospective studies are warranted to evaluate clinical measures to decrease the risk of POI among patients undergoing instrumented thoracolumbar spinal fusions.