✓ A biomembrane was developed from pig peritoneum treated with 0.65% glutaraldehyde. This was evaluated for use as a dural substitute in an animal model and in a patient population. After being treated with the glutaraldehyde solution, the biomembrane lost its antigenicity while its collagen underwent an irreversible cross-linking reaction, causing it to become a stable nonviable polymer resistant to absorption by the host. The biomembrane was used experimentally in 43 procedures on 20 dogs and was applied clinically in 614 patients. The results demonstrated that it is an acceptable material for the repair of dural defects, with the following advantages: 1) it is nontoxic to the body and brain tissues, with minimal tissue reaction; 2) its biophysical properties facilitate watertight closure with sutures; 3) its distensibility makes it suitable for decompressive surgical dural repair; and 4) its visceral surface is extremely smooth, causing virtually no adhesions with the brain tissue while the outer surface readily heals with the subcutaneous tissue.
Xu Bang-Zong, Pan Hong-Xue, Li Ke-Ming, Chen Xi-Jin, Tian Ying-Dei, Li Yong-Lin and Liu Jian
Lauren Conova, Jennifer Vernengo, Ying Jin, B. Timothy Himes, Birgit Neuhuber, Itzhak Fischer, Anthony Lowman, Jennifer Vernengo, Ying Jin, B. Timothy Himes, Birgit Neuhuber, Itzhak Fischer and Anthony Lowman
The authors investigated the feasibility of using injectable hydrogels, based on poly(N-isopropylacrylamide) (PNIPAAm), lightly cross-linked with polyethylene glycol (PEG) or methylcellulose (MC), to serve as injectable scaffolds for local delivery of neurotrophins and cellular transplants into the injured spinal cord. The primary aims of this work were to assess the biocompatibility of the scaffolds by evaluating graft cell survival and the host tissue immune response. The scaffolds were also evaluated for their ability to promote axonal growth through the action of released brain-derived neurotrophic factor (BDNF).
The in vivo performance of PNIPAAm-g-PEG and PNIPAAm-g-MC was evaluated using a rodent model of spinal cord injury (SCI). The hydrogels were injected as viscous liquids into the injury site and formed space-filling hydrogels. The host immune response and biocompatibility of the scaffolds were evaluated at 2 weeks by histological and fluorescent immunohistochemical analysis. Commercially available matrices were used as a control and examined for comparison.
Experiments showed that the scaffolds did not contribute to an injury-related inflammatory response. PNIPAAm-g-PEG was also shown to be an effective vehicle for delivery of cellular transplants and supported graft survival. Additionally, PNIPAAm-g-PEG and PNIPAAm-g-MC are permissive to axonal growth and can serve as injectable scaffolds for local delivery of BDNF.
Based on the results, the authors suggest that these copolymers are feasible injectable scaffolds for cell grafting into the injured spinal cord and for delivery of therapeutic factors.
Lauren Conova Grous, Jennifer Vernengo, Ying Jin, B. Timothy Himes, Jed S. Shumsky, Itzhak Fischer and Anthony Lowman
In a follow-up study to their prior work, the authors evaluated a novel delivery system for a previously established treatment for spinal cord injury (SCI), based on a poly(N-isopropylacrylamide) (PNIPAAm), lightly cross-linked with a polyethylene glycol (PEG) injectable scaffold. The primary aim of this work was to assess the recovery of both spontaneous and skilled forelimb function following a cervical dorsolateral funiculotomy in the rat. This injury ablates the rubrospinal tract (RST) but spares the dorsal and ventral corticospinal tract and can severely impair reaching and grasping abilities.
Animals received an implant of either PNIPAAm-g-PEG or PNIPAAm-g-PEG + brain-derived neurotrophic factor (BDNF). The single-pellet reach-to-grasp task and the staircase-reaching task were used to assess skilled motor function associated with reaching and grasping abilities, and the cylinder task was used to assess spontaneous motor function, both before and after injury.
Because BDNF can stimulate regenerating RST axons, the authors showed that animals receiving an implant of PNIPAAm-g-PEG with codissolved BDNF had an increased recovery rate of fine motor function when compared with a control group (PNIPAAm-g-PEG only) on both a staircase-reaching task at 4 and 8 weeks post-SCI and on a single-pellet reach-to-grasp task at 5 weeks post-SCI. In addition, spontaneous motor function, as measured in the cylinder test, recovered to preinjury values in animals receiving PNIPAAm-g-PEG + BDNF. Fluorescence immunochemistry indicated the presence of both regenerating axons and BDA-labeled fibers growing up to or within the host-graft interface in animals receiving PNIPAAm-g-PEG + BDNF.
Based on their results, the authors suggest that BDNF delivered by the scaffold promoted the growth of RST axons into the lesion, which may have contributed in part to the increased recovery rate.
Qiang Yuan, Xing Wu, Yirui Sun, Jian Yu, Zhiqi Li, Zhuoying Du, Ying Mao, Liangfu Zhou and Jin Hu
Some studies have demonstrated that intracranial pressure (ICP) monitoring reduces the mortality of traumatic brain injury (TBI). But other studies have shown that ICP monitoring is associated with increased mortality. Thus, the authors performed a meta-analysis of studies comparing ICP monitoring with no ICP monitoring in patients who have suffered a TBI to determine if differences exist between these strategies with respect to mortality, intensive care unit (ICU) length of stay (LOS), and hospital LOS.
The authors systematically searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials (Central) from their inception to October 2013 for relevant studies. Randomized clinical trials and prospective cohort, retrospective observational cohort, and case-control studies that compared ICP monitoring with no ICP monitoring for the treatment of TBI were included in the analysis. Studies included had to report at least one point of mortality in an ICP monitoring group and a no–ICP monitoring group. Data were extracted for study characteristics, patient demographics, baseline characteristics, treatment details, and study outcomes.
A total of 14 studies including 24,792 patients were analyzed. The meta-analysis provides no evidence that ICP monitoring decreased the risk of death (pooled OR 0.93 [95% CI 0.77–1.11], p = 0.40). However, 7 of the studies including 12,944 patients were published after 2012 (January 2012 to October 2013), and they revealed that ICP monitoring was significantly associated with a greater decrease in mortality than no ICP monitoring (pooled OR 0.56 [95% CI 0.41–0.78], p = 0.0006). In addition, 7 of the studies conducted in North America showed no evidence that ICP monitoring decreased the risk of death, similar to the studies conducted in other regions. ICU LOSs were significantly longer for the group subjected to ICP monitoring (mean difference [MD] 0.29 [95% CI 0.21–0.37]; p < 0.00001). In the pooled data, the hospital LOS with ICP monitoring was also significantly longer than with no ICP monitoring (MD 0.21 [95% CI 0.04–0.37]; p = 0.01).
In this systematic review and meta-analysis of ICP monitoring studies, the authors found that the current clinical evidence does not indicate that ICP monitoring overall is significantly superior to no ICP monitoring in terms of the mortality of TBI patients. However, studies published after 2012 indicated a lower mortality in patients who underwent ICP monitoring.
Xing Wu, Jin Hu, Liangfu Zhou, Ying Mao, Bojie Yang, Liang Gao, Rong Xie, Feng Xu, Dong Zhang, Jun Liu and Jianhong Zhu
Mesenchymal stem cells (MSCs) have been shown to migrate toward tumors, but their distribution pattern in gliomas has not been completely portrayed. The primary purpose of the study was to assay the tropism capacity of MSCs to gliomas, to delineate the pattern of MSC distribution in gliomas after systemic injection, and to track the migration and incorporation of magnetically labeled MSCs using 1.5-T magnetic resonance (MR) imaging.
The MSCs from Fischer 344 rats were colabeled with superparamagnetic iron oxide nanoparticles (SPIO) and enhanced green fluorescent protein (EGFP). The tropism capacity of MSCs was quantitatively assayed in vitro using the Transwell system. To track the migration of MSCs in vivo, MR imaging was performed both 7 and 14 days after systemic administration of labeled MSCs. After MR imaging, the distribution patterns of MSCs in rats with gliomas were examined using Prussian blue and fluorescence staining.
The in vitro study showed that MSCs possessed significantly greater migratory capacity than fibroblast cells (p < 0.001) and that lysis of F98 glioma cells and cultured F98 cells showed a greater capacity to induce migration of cells than other stimuli (p < 0.05). Seven days after MSC transplantation, the SPIO–EGFP colabeled cells were distributed throughout the tumor, where a well-defined dark hypointense region was represented on gradient echo sequences. After 14 days, most of the colabeled MSCs were found at the border between the tumor and normal parenchyma, which was represented on gradient echo sequences as diluted amorphous dark areas at the edge of the tumors.
This study demonstrated that systemically transplanted MSCs migrate toward gliomas with high specificity in a temporal–spatial pattern, which can be tracked using MR imaging.
Abudumijiti Aibaidula, Wang Zhao, Jin-song Wu, Hong Chen, Zhi-feng Shi, Lu-lu Zheng, Ying Mao, Liang-fu Zhou and Guo-dong Sui
Conventional methods for isocitrate dehydrogenase 1 (IDH1) detection, such as DNA sequencing and immunohistochemistry, are time- and labor-consuming and cannot be applied for intraoperative analysis. To develop a new approach for rapid analysis of IDH1 mutation from tiny tumor samples, this study used microfluidics as a method for IDH1 mutation detection.
Forty-seven glioma tumor samples were used; IDH1 mutation status was investigated by immunohistochemistry and DNA sequencing. The microfluidic device was fabricated from polydimethylsiloxane following standard soft lithography. The immunoanalysis was conducted in the microfluidic chip. Fluorescence images of the on-chip microcolumn taken by the charge-coupled device camera were collected as the analytical results readout. Fluorescence signals were analyzed by NIS-Elements software to gather detailed information about the IDH1 concentration in the tissue samples.
DNA sequencing identified IDH1 R132H mutation in 33 of 47 tumor samples. The fluorescence signal for IDH1-mutant samples was 5.49 ± 1.87 compared with 3.90 ± 1.33 for wild type (p = 0.005). Thus, microfluidics was capable of distinguishing IDH1-mutant tumor samples from wild-type samples. When the cutoff value was 4.11, the sensitivity of microfluidics was 87.9% and the specificity was 64.3%.
This new approach was capable of analyzing IDH1 mutation status of tiny tissue samples within 30 minutes using intraoperative microsampling. This approach might also be applied for rapid pathological diagnosis of diffuse gliomas, thus guiding personalized resection.