Development of an integrated CAD–FEA system for patient-specific design of spinal cages

Spinal cages are used to create a suitable mechanical environment for interbody fusion in cases of degenerative spinal instability. Due to individual variations in bone structures and pathological conditions, patient-specific cages can provide optimal biomechanical conditions for fusion, strengthening patient recovery. Finite element analysis (FEA) is a valuable tool in the biomechanical evaluation of patient-specific cage designs, but the time- and labor-intensive process of modeling limits its clinical application. In an effort to facilitate the design and analysis of patient-specific spinal cages, an integrated CAD–FEA system (CASCaDeS, comprehensive analytical spinal cage design system) was developed. This system produces a biomechanical-based patient-specific design of spinal cages and is capable of rapid implementation of finite element modeling. By comparison with commercial software, this system was validated and proven to be both accurate and efficient. CASCaDeS can be used to design patient-specific cages with a superior biomechanical performance to commercial spinal cages.     

A multi-body dynamics study on a weight-drop test of rat brain injury

Traumatic brain injury (TBI), induced by impact of an object with the head, is a major health problem worldwide. Rats are a well-established animal analogue for study of TBI and the weight-drop impact-acceleration (WDIA) method is a well-established model in rats for creating diffuse TBI, the most common form of TBI seen in humans. However, little is known of the biomechanics of the WDIA method and, to address this, we have developed a four-degrees-of-freedom multi-body mass-spring-damper model for the WDIA test in rats. An analytical expression of the maximum skull acceleration, one of the important head injury predictor, was derived and it shows that the maximum skull acceleration is proportional to the impact velocity but independent of the impactor mass. Furthermore, a dimensional analysis disclosed that the maximum force on the brain and maximum relative displacement between brain and skull are also linearly proportional to impact velocity. Additionally, the effects of the impactor mass were examined through a parametric study from the developed multi-body dynamics model. It was found that increasing impactor mass increased these two brain injury predictors.     

Involvement of Nox2 and Nox4 NADPH oxidases in early brain injury after subarachnoid hemorrhage

Oxidative stress is responsible for a poor prognosis of subarachnoid hemorrhage (SAH) patients. Nox2 has been shown to participate in SAH-induced early brain injury (EBI). Nox4 is another major subtype of Nox family widely expressed in central nervous system (CNS). Here, we investigated the role of Nox4 and whether there was a synergistic effect of Nox2 and Nox4 in SAH-induced EBI. Clinical brain biopsies of four patients with traumatic brain injury (TBI) and perihematomal brain tissue from six subjects with SAH were examined. Gp91ds-tat (a specific inhibitor of Nox2), GKT137831 (a specific inhibitor of Nox4), and apocynin (a non-specific Nox inhibitor) were used to test the role of Nox2 and Nox4. The protein levels of Nox2 and Nox4 were elevated in rat neurons and astrocytes at 12?h after SAH, and in cultured brain microvascular endothelial cells at 24?h after exposure to OxyHb. Similarly, there were higher Nox2 and Nox4 protein levels in perihematomal neurons and astrocytes in SAH patients than that in brain tissue from subjects with TBI. In SAH rat model, gp91ds-tat and GKT137831 could reduce SAH-induced neuronal death and degeneration, whereas apocynin did not induce a more intense neuroprotection. Consistently, in in vitro SAH model, siRNA-mediated silencing of Nox2 and Nox4 suppressed the OxyHb-induced neuronal apoptosis, whereas Nox2 and Nox4 co-knockdown also did not show a remarkable overlay effect. In conclusion, Nox4 should contribute to the pathological processes in SAH-induced EBI, and there was not an overlay effect of Nox2 inhibition and Nox4 inhibition on preventing SAH-induced EBI.     

The neuronal differentiation microenvironment is essential for spinal cord injury repair

Spinal cord injury (SCI) often leads to substantial disability due to loss of motor function and sensation below the lesion. Neural stem cells (NSCs) are a promising strategy for SCI repair. However, NSCs rarely differentiate into neurons; they mostly differentiate into astrocytes because of the adverse microenvironment present after SCI. We have shown that myelin-associated inhibitors (MAIs) inhibited neuronal differentiation of NSCs. Given that MAIs activate epidermal growth factor receptor (EGFR) signaling, we used a collagen scaffold-tethered anti-EGFR antibody to attenuate the inhibitory effects of MAIs and create a neuronal differentiation microenvironment for SCI repair. The collagen scaffold modified with anti-EGFR antibody prevented the inhibition of NSC neuronal differentiation by myelin. After transplantation into completely transected SCI animals, the scaffold-linked antibodies induced production of nascent neurons from endogenous and transplanted NSCs, which rebuilt the neuronal relay by forming connections with each other or host neurons to transmit electrophysiological signals and promote functional recovery. Thus, a scaffold-based strategy for rebuilding the neuronal differentiation microenvironment could be useful for SCI repair.     

Improvement in Double Staining With Fluoro-Jade C and Fluorescent Immunostaining: FJC Staining Is Not Specific to Degenerating Mature Neurons

Fluoro-Jade C (FJC) staining has been used to detect degenerating neurons in tissue sections. It is a simple and easy staining procedure and does not depend on the manner of cell death. In some experiments, double staining with FJC and fluorescent immunostaining (FI) is required to identify cell types. However, pretreatment for FJC staining contains some processes that are harsh to fluorophores, and the FI signal is greatly reduced. To overcome this issue, we improved the double staining protocol to acquire clear double-stained images by introducing the labeled streptavidin–biotin system. In addition, several studies indicate that FJC can label non-degenerating glial cells, including resting/reactive astrocytes and activated microglia. Moreover, our previous study indicated that degenerating mesenchymal cells were also labeled by FJC, but it is still unclear whether FJC can label degenerating glial cells. Acute encephalopathy model mice contained damaged astrocytes with clasmatodendrosis, and 6-aminonicotinamide-injected mice contained necrotic astrocytes and oligodendrocytes. Using our improved double staining protocol with FJC and FI, we detected FJC-labeled degenerating astrocytes and oligodendrocytes with pyknotic nuclei. These results indicate that FJC is not specific to degenerating neurons in some experimental conditions:     

CGRP is essential for protection against alveolar epithelial cell necroptosis by activating the AMPK/L-OPA1 signaling pathway during acute lung injury

Alveolar epithelial cell (AEC) necroptosis is critical to disrupt the alveolar barrier and provoke acute lung injury (ALI). Here, we define calcitonin gene-related peptide (CGRP), the most abundant endogenous neuropeptide in the lung, as a novel modulator of AEC necroptosis in lipopolysaccharide (LPS)-induced ALI. Upon LPS-induced ALI, overexpression of Cgrp significantly mitigates the inflammatory response, alleviates lung tissue damage, and decreases AEC necroptosis. Similarly, CGRP alleviated AEC necroptosis under the LPS challenge in vitro. Previously, we identified that long optic atrophy 1 (L-OPA1) deficiency mediates mitochondrial fragmentation, leading to AEC necroptosis. In this study, we discovered that CGRP positively regulated mitochondrial fusion through stabilizing L-OPA1. Mechanistically, we elucidate that CGRP activates AMP-activated protein kinase (AMPK). Furthermore, the blockade of AMPK compromised the protective effect of CGRP against AEC necroptosis following the LPS challenge. Our study suggests that CRGP-mediated activation of the AMPK/L-OPA1 axis may have potent therapeutic benefits for patients with ALI or other diseases with necroptosis.     

Kiwifruit extracts inhibit cytokine production by lipopolysaccharide-activated macrophages, and intestinal epithelial cells isolated from IL10 gene deficient mice

Inflammatory bowel disease (IBD) is a chronic, inflammatory disorder of the gastrointestinal tract involving an inappropriate immune response to commensal microorganisms in a genetically susceptible host. This study examined the effects of aqueous and ethyl acetate extracts of gold kiwifruit (Actinidia chinensis) or green kiwifruit (Actinidia deliciosa) using in vitro models of IBD. These models comprised primary macrophages and intestinal epithelial cells isolated from C57BL/5J and interleukin-10 gene deficient (Il10^−/−) mice and RAW 264.7, a murine macrophage-like cell line. All four kiwifruit extracts reduced the activation of these models after lipopolysaccharide stimulation, decreasing nitric oxide and cytokine secretion by both Il10^−/− and wild-type cells. The ethyl acetate extracts exhibited the highest anti-inflammatory activity, with almost complete suppression of lipopolysaccharide-stimulated macrophage activation. These results suggest that kiwifruit extracts have significant anti-inflammatory activity relevant to IBD. We suggest that the Il10^−/− mouse is a suitable model for further study of these compounds.     

Cryopreservation of buffy-coat-derived platelet concentrates in dimethyl sulfoxide and platelet additive solution

Platelets prepared in plasma can be frozen in 6% dimethyl sulfoxide (Me₂SO) and stored for extended periods at −80 °C. The aim of this study was to reduce the plasma present in the cryopreserved product, by substituting plasma with platelet additive solution (PAS; SSP+), whilst maintaining in vitro platelet quality. Buffy coat-derived pooled leukoreduced platelet concentrates were frozen in a mixture of SSP+, plasma and 6% Me₂SO. The platelets were concentrated, to avoid post-thaw washing, and frozen at −80 °C. The cryopreserved platelet units (n = 9) were rapidly thawed at 37 °C, reconstituted in 50% SSP+/plasma and stored at 22 °C. Platelet recovery and quality were examined 1 and 24 h post-thaw and compared to the pre-freeze samples. Upon thawing, platelet recovery ranged from 60% to 80%. However, there were differences between frozen and liquid-stored platelets, including a reduction in aggregation in response to ADP and collagen; increased CD62P expression; decreased viability; increased apoptosis and some loss of mitochondrial membrane integrity. Some recovery of these parameters was detected at 24 h post-thaw, indicating an extended shelf-life may be possible. The data suggests that freezing platelets in 6% Me₂SO and additive solution produces acceptable in vitro platelet quality.