Postoperative Complications and Survival Rate in Hemodialysis-Dependent Patients Undergoing Cervical Spine Surgery.

Introduction: Spine surgery is challenging in hemodialysis (HD)-dependent patients owing to their poor general condition. However, postoperative complications and the mortality and survival rates have not been specifically evaluated in a wide series. This study aimed to elucidate postoperative complications and the survival rate in cervical spine surgery in HD patients. Methods: This study included 109 HD patients (70 men, 39 women) who had undergone cervical spine surgery between July 1996 and May 2018. Based on radiological diagnosis, we divided them into the destructive spondyloarthropathy (DSA) and non-DSA groups. We investigated the causes of hemodialysis, postoperative complications, postoperative inpatient mortality rate, and survival rate. Results: The DSA and non-DSA groups included 100 surgeries in 89 patients and 21 surgeries in 20 patients, respectively. The mean age at surgery was 62.9 years for the DSA and 55.9 years for the non-DSA group (P=0.97). The DSA group had a shorter hemodialysis period at surgery compared with the non-DSA group (21.7 vs. 26.5 years, P<0.05). The two most common causes of HD in both groups were chronic glomerulonephritis (DSA, 45%; non-DSA, 57.1%) and diabetes (DSA, 11%; non-DSA, 14.5%). Postoperative complications were observed in 23% (23/100) and 19% (4/21) of surgeries in the DSA and non-DSA groups, respectively (P=0.782). The total in-hospital mortality rate was 2.5% (3/121). The 1-, 3-, 5-, and 10-year postoperative survival rates of all patients were 89.6%, 75.5%, 67.1%, and 44.7%, respectively. The survival rates did not depend on the group (DSA vs. non-DSA), pre- and postoperative Japanese Orthopedic Association score for cervical myelopathy, hemodialysis period, sex, and age (P>0.05). However, significantly low survival rates were observed in HD caused by diabetes compared with that by chronic glomerulonephritis (P<0.001) and other causes (P<0.001). Conclusions: Cervical spine surgery in HD patients is associated with postoperative complications. The postoperative survival rate was found to be low if the cause of hemodialysis was diabetes.

Development of Prodrug Type Circular siRNA for In Vivo Knockdown by Systemic Administration.

siRNAs are being developed as a novel therapeutic modality; however, problems impeding their application in extrahepatic tissues persist, including inadequate stability in biological environments and inefficient drug delivery system to target tissues. Thus, technological improvements that enable robust silencing of target messenger RNA (mRNA) in extrahepatic tissues are necessary. We developed prodrug type covalently closed siRNA (circular siRNA) as a novel nucleic acid agent to knockdown target genes in extrahepatic tissues by systemic administration without drug delivery components. Circular siRNA, which is chemically synthesizable, can assume optimal structures for efficient knockdown using its cleavable linker; namely, circular and linear structure in extracellular and intracellular environment, respectively. In this study, we investigated circular siRNA physicochemical properties, knockdown mechanism, and characteristics in vitro, as well as pharmacokinetics, accumulation, knockdown activity, and safety in vivo. Our circular siRNA exhibited higher stability against serum and exonucleases, increased cellular uptake, and stronger knockdown activity without transfection reagent in vitro than linear siRNA. Furthermore, after systemic administration to mice, circular siRNA showed prolonged circulation and improved knockdown activity in the liver, kidney, and muscle, without causing adverse effects. Circular siRNA may represent an additional platform for RNAi therapeutics, providing alternate solutions for disease treatment.

Comparison of Atlantoaxial Fusion with Transarticular Screws and C1 Lateral Mass-C2 Screws Using Intraoperative O-Arm Navigation.

OBJECTIVE: This study compared the surgical outcomes of atlantoaxial fusion with transarticular screws (TASs) and C1 lateral mass-C2 screws (screw-rod constructs [SRCs]) using the intraoperative O-arm navigation system (O-arm). METHODS: Among a total of 28 patients who underwent atlantoaxial fixation, 13 underwent TAS fixation and 15 underwent SRC fixation using the O-arm. All patients underwent Brooks procedure with iliac bone graft in addition to screw fixation. TAS fixation was performed for cases without high-riding vertebral artery (hVA). In the SRC group, pars or lamina screws were inserted for the side with a C2 hVA. Operative time, intraoperative bleeding, perioperative complications, screw accuracy, and bone union were evaluated. RESULTS: There were statistically significant differences in mean operative time between the 2 procedures (166 minutes in the TAS group vs. 212 minutes in the SRC group, P < 0.05) and in mean blood loss (80 vs. 185 mL, respectively; P < 0.01). Two patients developed temporary postoperative occipital neuralgia probably related to C2 nerve root in the SRC group. No screws violated the cortex in either group. Complete bone union was observed in all cases. CONCLUSIONS: O-arm-assisted TAS fixation had less intraoperative blood loss, shorter operative time, and fewer screw insertion complications than O-arm-assisted SRC fixation. O-arm-assisted TAS fixation is preferable for atlantoaxial fusion in patients without hVA.

Surgical Results of Intraoperative C-arm Fluoroscopy Versus O-arm in Transarticular Screw Fixation for Atlantoaxial Instability.

OBJECTIVE: This study compared the surgical results of transarticular screw (TAS) fixation for atlantoaxial instability between C-arm fluoroscopy and O-arm. METHODS: Of 58 patients who underwent TAS fixation for atlantoaxial instability, 35 underwent C-arm-assisted surgery (C-group) and 23 underwent O-arm-assisted surgery (O-group). In total, 78 TASs were placed: 39 in the C-group and 39 in the O-group. Unilateral and bilateral TAS fixation was performed in 38 and 20 patients, respectively. All patients underwent Brook's procedure with TAS. TAS fixation accuracy on postoperative computed tomography, operative time, intraoperative bleeding, perioperative complications, and bone union were evaluated. Screw accuracy was assessed using Neo's classification: grade (G) 0, no perforation; G1, perforation <2 mm; G2, perforation 2-4 mm; G3, perforation >4 mm. RESULTS: TAS fixation accuracy was greater in the O-group than the C-group: G0: 38, 97.4%; G1: 1, 2.6% (O-group) vs G0: 22, 56.4%; G1: 11, 28.2%; G2: 3, 7.7%; G3: 3, 7.7% (C-group) (P < 0.001). Median operative time and median blood loss were similar between both groups. Bone union rate was greater with bilateral than unilateral TAS fixation (P < 0.05). There were no complications regarding screw malposition. Deep wound infection was observed in 1 case in the C-group. CONCLUSIONS: O-arm use improved TAS fixation accuracy. Blood loss was equivalent between the groups. O-arm-assisted TAS fixation did not prolong operative time despite the time required for setting and scanning. The O-arm is safe and useful for TAS fixation in atlantoaxial instability.

Cervical Pedicle Screw Insertion Using O-Arm-Based 3D Navigation: Technical Advancement to Improve Accuracy of Screws.

OBJECTIVE: This study aimed to report the technical advancement to improve the accuracy of cervical pedicle screw (CPS) placement using O-arm-based 3D navigation. METHODS: Sixty-four patients who underwent CPS using O-arm in the spine level of C2 to C7 between June 2013 and February 2020 were involved. In the first phase, a reference frame was placed onto the spinous process of the cranial vertebrae and used it at a maximum of 3 vertebral levels. The navigation guide sleeve was used to drill a screw hole. In the second phase, a reference frame that can hold 3 vertebrae was introduced. In the third phase, a drill guide sleeve to minimize bending of the drill tip was developed. In the fourth phase, navigated surgical drill was introduced. Screw accuracy was assessed using Neo classification: grade (G) 0, no perforation; G1, perforation <2 mm; G2, perforation 2-4 mm; and G3, perforation >4 mm. RESULTS: Mean age at surgery was 67 (19-88) years. A total of 317 CPSs were inserted. In total, 83 screws were inserted in the first phase, 60 in the second phase, 87 in the third phase, and 87 in the fourth phase. The total proportion of malpositioning was 3.8% (12/317 screws) and all were G1; 6.0% (5/83 screws) in the first phase, 8.3% (5/60 screws) in the second phase, 1.2% (1/87 screws) in the third phase, and 1.2% (1/87 screws) in the fourth phase (P < 0.05). CONCLUSIONS: O-arm use improved CPS placement accuracy with the advancement of techniques and instruments.

PEG-modification on the endo-position of an antisense oligonucleotide increases tumor accumulation via the EPR effect.

Nucleic acid medicine is the next-generation therapeutic modality for refractory diseases with its unique mode of action as an alternative to traditional therapies. A nucleic acid delivery system targeted to liver was validated clinically; however, the delivery system of nucleic acids targeting solid tumors following systemic administration is not efficient enough for clinical use. In this study, we first utilized an antisense oligonucleotide (ASO) and polyethylene glycol (PEG) in one-to-one conjugation (PEG-ASO) at the endo-position of the ASO (endo-PEG-ASO). The effects of ASO modification position, PEG structure and molecular weight, and PEG-ASO tumor accumulation were evaluated in vivo. The endo-PEG-ASO showed prolonged pharmacokinetics and enhanced tumor accumulation compared with the conventional ASO and the PEG-ASO modified at the ASO exo-position (exo-PEG-ASO), indicating that the modification position of PEG is crucial for targeting tumors. We also observed that the endo-PEG-ASO indicated possibility of enhanced permeability inside the tumor. Further research is needed to optimize the linker in the endo-PEG-ASO for clinical application as a novel and promising therapeutic format for targeting solid tumors.

The intratracheal administration of locked nucleic acid containing antisense oligonucleotides induced gene silencing and an immune-stimulatory effect in the murine lung.

Locked nucleic acid containing antisense oligonucleotides (LNA-ASOs) have the potential to modulate the disease-related gene expression by the RNaseH-dependent degradation of mRNAs. Pulmonary drug delivery has been widely used for the treatment of lung disease. Thus, the inhalation of LNA-ASOs is expected to be an efficient therapy that can be applied to several types of lung disease. Because the lung has a distinct immune system against pathogens, the immune-stimulatory effect of LNA-ASOs should be considered for the development of novel inhaled LNA-ASOs therapies. However, there have been no reports on the relationship between knock-down (KD) and the immune-stimulatory effects of inhaled LNA-ASOs in the lung. In this report, LNA-ASOs targeting Scarb1 (Scarb1-ASOs) or negative control LNA-ASOs targeting ApoB (ApoB-ASOs) were intratracheally administered to mice to investigate the KD of the gene expression and the immune-stimulatory effects in the lung. We confirmed that the intratracheal administration of Scarb1-ASOs exerted a KD effect in the lung without a drug delivery system. On the other hand, both Scarb1-ASOs and ApoB-ASOs induced neutrophilic infiltration in the alveoli and increased the expression levels of G-CSF and CXCL1 in the lung. The dose required for KD was the same as the dose that induced the neutrophilic immune response. In addition, in our in vitro experiments, Scarb1-ASOs did not increase the G-CSF or CXCL1 expression in primary lung cells, even though Scarb1-ASOs exerted a strong KD effect. Hence, we hypothesize that inhaled LNA-ASOs have the potential to exert a KD effect in the lung, but that they may be associated with a risk of immune stimulation. Further studies about the mechanism underlying the immune-stimulatory effect of LNA-ASOs is necessary for the development of novel inhaled LNA-ASO therapies.

In vivo gene transfer using pDNA/chitosan/chondroitin sulfate ternary complexes: influence of chondroitin sulfate on the stability of freeze-dried complexes and transgene expression in vivo.

BACKGROUND: Chitosan has been investigated as a promising nonviral vector. However, several problems still remain, such as a relatively low transfection efficiency and instability under physiological conditions. We previously demonstrated that a chondroitin sulfate (CS) coating enhanced the transfection efficiency and physicochemical stability of plasmid DNA (pDNA)/chitosan complexes in vitro. In the present study, the effects of coating pDNA/chitosan complexes with CS on the stability in freeze-dry rehydration processes and gene expression in vivo were investigated. METHODS: Freeze-drying storage at -20 °C, 4 °C, or room temperature, freezing storage at -20 °C, or liquid storage at 4 °C or room temperature, were examined for preservation conditions of pDNA/chitosan/CS ternary complexes by a gel retardation assay, measurements of sizes and zeta potentials, and a luciferase assay. Moreover, to determine the transfection efficiency of the ternary complexes in vivo, suicide gene therapy was carried out in Huh-7-implanted mice using herpes simplex virus thymidine kinase coding pDNA and ganciclovir. RESULTS: The freeze-dried pDNA/chitosan/CS ternary complexes showed sufficient cell transfection ability in vitro and in vivo. In addition, ternary complexes were associated with a significant suppression of tumor growth and a histopathologically high anti-tumor effect by intratumoral injection to tumor-bearing mice. CONCLUSIONS: The CS coating enhanced the preservation stability of the pDNA/chitosan complexes after freeze-drying-rehydration and their transgene expression in vivo.

The effects of coating pDNA/chitosan complexes with chondroitin sulfate on physicochemical characteristics and cell transfection.

pDNA/chitosan complexes have been investigated as promising non-viral vectors for gene delivery. However, an increase in transfection efficiency and enhancement of physicochemical stability are required for their practical use. In this study, chondroitin sulfate (CS) was employed as a coating agent to increase the stability and transfection efficiency of a pDNA/chitosan complex. The pDNA/chitosan/CS ternary complexes formed with six kinds of CSs having different limiting viscosities (0.2-1.6) and sulfation degrees (5.0-7.0%) showed considerable differences in particle size, surface charge, and morphology. Among them, CS having a medium limiting viscosity (0.5-0.6) and a high sulfation degree (6.9%) showed significant enhancements in cell transfection efficiency. Analyses of cellular uptake and intracellular trafficking revealed that increased cellular uptake via macropinocytosis, together with reduced entry into lysosomes, may explain the promotion of transfection efficiency of ternary complexes.

Physicochemical properties of pDNA/chitosan complexes as gene delivery systems.

Successful gene therapy depends on the development of effective gene carriers. Naturally occurring chitosan has been employed widely as a non-viral gene carrier because of its low toxicity, low immunogenicity, biocompatibility, and biodegradability. In this review, we summarize the utilization of chitosan, modified chitosan, and chitosan-containing ternary complexes as gene carriers. In particular, we discuss the influence of the physicochemical features of pDNA/chitosan complexes on their functions, such as stability and gene transfer into cells.