Mild Traumatic Brain Injury and Subsequent Acute Pulmonary Inflammatory Response

Modeling of the brain-lung axis using organoids in traumatic brain injury: an updated review

Clinical outcome after traumatic brain injury (TBI) is closely associated conditions of other organs, especially lungs as well as degree of brain injury. Even if there is no direct lung damage, severe brain injury can enhance sympathetic tones on blood vessels and vascular resistance, resulting in neurogenic pulmonary edema. Conversely, lung damage can worsen brain damage by dysregulating immunity. These findings suggest the importance of brain-lung axis interactions in TBI. However, little research has been conducted on the topic. An advanced disease model using stem cell technology may be an alternative for investigating the brain and lungs simultaneously but separately, as they can be potential candidates for improving the clinical outcomes of TBI.In this review, we describe the importance of brain-lung axis interactions in TBI by focusing on the concepts and reproducibility of brain and lung organoids in vitro. We also summarize recent research using pluripotent stem cell-derived brain organoids and their preclinical applications in various brain disease conditions and explore how they mimic the brain-lung axis. Reviewing the current status and discussing the limitations and potential perspectives in organoid research may offer a better understanding of pathophysiological interactions between the brain and lung after TBI.

Nature vs. Manmade: Comparing Exosomes and Liposomes for Traumatic Brain Injury

Traumatic brain injury (TBI) of all severities is a significant public health burden, causing a range of effects that can lead to death or a diminished quality of life. Liposomes and mesenchymal stem cell-derived exosomes are two drug delivery agents with potential to be leveraged in the treatment of TBI by increasing the efficacy of drug therapies as well as having additional therapeutic effects. They exhibit several physical similarities, but key differences affect their performances as nanocarriers. Liposomes can be produced commercially at scale, and liposomes achieve higher encapsulation efficiency. Meanwhile, the intrinsic cargo and targeting moieties of exosomes, which liposomes lack, give exosomes a greater ability to facilitate neural regeneration, and exosomes do not trigger the infusion reactions that liposomes can. However, there are concerns about both exosomes and liposomes regarding interactions with tumors. The same routes of administration can be used for both exosomes and liposomes, resulting in somewhat different distribution throughout the body. While the effect of the nanocarrier type on accumulation in the brain is not concrete, targeting leads to increased accumulation of both exosomes and liposomes in the brain, upon which on-demand release can be used for both drug deliverers. Although neither have been applied to TBI in humans, preclinical trials have shown their immense potential, as have clinical trials pertaining to other brain injuries and conditions. While questions remain, research thus far shows that the various differences make exosomes a better choice of nanocarrier for TBI.

Therapeutic Effect of a Hydrogel-based Neural Stem Cell Delivery Sheet for Mild Traumatic Brain Injury

OBJECTIVE

There are no effective clinically applicable treatments for neuronal dysfunction after mild traumatic brain injury (TBI). Here, we evaluated the therapeutic effect of a new delivery method of mouse neural stem cell (mNSC) spheroids using a hydrogel, in terms of improvement in damaged cortical lesions and cognitive impairment after mild TBI.

METHODS

mNSCs were isolated from the subventricular zone and subgranular zone by a hydrogel-based culture system. GFP-transduced mNSCs were generated into spheroids and wrapped into a sheet for transplantation. Male C57BL/6J mice were randomly divided into four groups: sham operation, TBI, TBI with mNSC spheroids, and TBI with mNSC spheroid sheet transplantation covering the damaged cortex. Histopathological and immunohistochemical features and cognitive function were evaluated 7, 14, and 28 days after transplantation following TBI.

RESULTS

Hydrogel-based culture systems and mNSC isolation were successfully established from the adult mice. Essential transcription factors for NSCs, such as SOX2, PAX6, Olig2, nestin, and doublecortin (DCX), were highly expressed in the mNSCs. A transplanted hydrogel-based mNSC spheroid sheet showed good engraftment and survival ability, differentiated into TUJ1-positive neurons, promoted angiogenesis, and reduced neuronal degeneration. Also, TBI mice treated with mNSC spheroid sheet transplantation exhibited a significantly increased preference for a new object, suggesting improved cognitive function compared to the mNSC spheroids or no treatment groups.

CONCLUSION

Transplantation with a hydrogel-based mNSC spheroid sheet showed engraftment, migration, and stability of delivered cells in a hostile microenvironment after TBI, resulting in improved cognitive function via reconstruction of the damaged cortex.

STATEMENT OF SIGNIFICANCE

This study presents the therapeutic effect of a new delivery method of mouse neural stem cells spheroids using a hydrogel, in terms of improvement in damaged cortical lesions and cognitive impairment after traumatic brain injury. Collagen/fibrin hydrogel allowed long-term survival and migratory ability of NSCs spheroids. Furthermore, transplanted hydrogel-based mNSCs spheroids sheet showed good engraftment, migration, and stability of delivered cells in a hostile microenvironment, resulting in reconstruction of the damaged cortex and improved cognitive function after TBI. Therefore, we suggest that a hydrogel-based mNSCs spheroids sheet could help to improve cognitive impairment after TBI.

The Central Fluid Percussion Brain Injury in a Gyrencephalic Pig Brain: Scalable Diffuse Injury and Tissue Viability for Glial Cell Immunolabeling following Long-Term Refrigerated Storage

Traumatic brain injury (TBI) affects millions of people annually; however, our knowledge of the diffuse pathologies associated with TBI is limited. As diffuse pathologies, including axonal injury and neuroinflammatory changes, are difficult to visualize in the clinical population, animal models are used. In the current study, we used the central fluid percussion injury (CFPI) model in a micro pig to study the potential scalability of these diffuse pathologies in a gyrencephalic brain of a species with inflammatory systems very similar to humans. We found that both axonal injury and microglia activation within the thalamus and corpus callosum are positively correlated with the weight-normalized pressure pulse, while subtle changes in blood gas and mean arterial blood pressure are not. We also found that the majority of tissue generated up to 10 years previously is viable for immunofluorescent labeling after long-term refrigeration storage. This study indicates that a micro pig CFPI model could allow for specific investigations of various degrees of diffuse pathological burdens following TBI.

Human embryonic stem cell-derived cerebral organoids for treatment of mild traumatic brain injury in a mouse model

OBJECTIVE

There are no effective treatments for relieving neuronal dysfunction after mild traumatic brain injury (TBI). Here, we evaluated therapeutic efficacy of human embryonic stem cell-derived cerebral organoids (hCOs) in a mild TBI model, in terms of repair of damaged cortical regions, neurogenesis, and improved cognitive function.

METHODS

Male C57BL/6 J mice were randomly divided into sham-operated, mild TBI, and mild TBI with hCO groups. hCOs cultured at 8 weeks were used for transplantation. Mice were sacrificed at 7 and 14 days after transplantation followed by immunofluorescence staining, cytokine profile microarray, and novel object recognition test.

RESULTS

8W-hCOs transplantation significantly reduced neuronal cell death, recovered microvessel density, and promoted neurogenesis in the ipsilateral subventricular zone and dentate gyrus of hippocampus after mild TBI. In addition, increased angiogenesis into the engrafted hCOs was observed. Microarray results of hCOs revealed neuronal differentiation potential and higher expression of early brain development proteins associated with neurogenesis, angiogenesis and extracellular matrix remodeling. Ultimately, 8W-hCO transplantation resulted in reconstruction of damaged cortex and improvement in cognitive function after mild TBI.

CONCLUSION

hCO transplantation may be feasible for treating mild TBI-related neuronal dysfunction via reconstruction of damaged cortex and neurogenesis in the hippocampus.