Adenovirus-mediated transfer and expression of beta-gal in injured hippocampus after traumatic brain injury in mice

Old and Promising Markers Related to Autophagy in Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the first causes of death and disability in the world. Because of the lack of macroscopical or histologic evidence of the damage, the forensic diagnosis of TBI could be particularly difficult. Considering that the activation of autophagy in the brain after a TBI is well documented in literature, the aim of this review is to find all autophagy immunohistological protein markers that are modified after TBI to propose a method to diagnose this eventuality in the brain of trauma victims. A systematic literature review on PubMed following PRISMA 2020 guidelines has enabled the identification of 241 articles. In all, 21 of these were enrolled to identify 24 markers that could be divided into two groups. The first consisted of well-known markers that could be considered for a first diagnosis of TBI. The second consisted of new markers recently proposed in the literature that could be used in combination with the markers of the first group to define the elapsed time between trauma and death. However, the use of these markers has to be validated in the future in human tissue by further studies, and the influence of other diseases affecting the victims before death should be explored.

Senescence-associated-β-galactosidase staining following traumatic brain injury in the mouse cerebrum

Primary and secondary traumatic brain injury (TBI) can cause tissue damage by inducing cell death pathways including apoptosis, necroptosis, and autophagy. However, similar pathways can also lead to senescence. Senescent cells secrete senescence-associated secretory phenotype proteins following persistent DNA damage response signaling, leading to cell disorders. TBI initially activates the cell cycle followed by the subsequent triggering of senescence. This study aims to clarify how the mRNA and protein expression of different markers of cell cycle and senescence are modulated and switched over time after TBI. We performed senescence-associated-β-galactosidase (SA-β-gal) staining, immunohistochemical analysis, and real-time PCR to examine the time-dependent changes in expression levels of proteins and mRNA, related to cell cycle and cellular senescence markers, in the cerebrum during the initial 14 days after TBI using a mouse model of controlled cortical impact (CCI). Within the area adjacent to the cerebral contusion after TBI, the protein and/or mRNA expression levels of cell cycle markers were increased significantly until 4 days after injury and senescence markers were significantly increased at 4, 7, and 14 days after injury. Our findings suggested that TBI initially activated the cell cycle in neurons, astrocytes, and microglia within the area adjacent to the hemicerebrum contusion in TBI, whereas after 4 days, such cells could undergo senescence in a cell-type-dependent manner.

Cell and gene therapies for refractory epilepsy

Despite recent advances in the development of antiepileptic drugs, refractory epilepsy remains a major clinical problem affecting up to 35% of patients with partial epilepsy. Currently, there are few therapies that affect the underlying disease process. Therefore, novel therapeutic concepts are urgently needed. The recent development of experimental cell and gene therapies may offer several advantages compared to conventional systemic pharmacotherapy: (i) Specificity to underlying pathogenetic mechanisms by rational design; (ii) specificity to epileptogenic networks by focal delivery; and (iii) avoidance of side effects. A number of naturally occurring brain substances, such as GABA, adenosine, and the neuropeptides galanin and neuropeptide Y, may function as endogenous anticonvulsants and, in addition, may interact with the process of epileptogenesis. Unfortunately, the systemic application of these compounds is compromised by limited bioavailability, poor penetration of the blood-brain barrier, or the widespread systemic distribution of their respective receptors. Therefore, in recent years a new field of cell and gene-based neuropharmacology has emerged, aimed at either delivering endogenous anticonvulsant compounds by focal intracerebral transplantation of bioengineered cells (ex vivo gene therapy), or by inducing epileptogenic brain areas to produce these compounds in situ (in vivo gene therapy). In this review, recent efforts to develop GABA-, adenosine-, galanin-, and neuropeptide Y- based cell and gene therapies are discussed. The neurochemical rationales for using these compounds are discussed, the advantages of focal applications are highlighted and preclinical cell transplantation and gene therapy studies are critically evaluated. Although many promising data have been generated recently, potential problems, such as long-term therapeutic efficacy, long-term safety, and efficacy in clinically relevant animal models, need to be addressed before clinical applications can be contemplated.

The potential application of gene therapy in the treatment of traumatic brain injury

Advances in molecular biology have allowed the possibility of using gene therapy in the treatment of traumatic brain injury. The major tactics involve picking out the appropriate gene target and, by controlling its specific regional expression, inhibiting neuronal cell deaths and/or promoting neuronal regeneration. This review addresses the preliminary usage of gene therapy in in vitro experiments and in animal models to treat traumatic brain injury. The gene targets with therapeutic potentials, the vectors that can be employed to deliver the candidate genes, as well as different approaches for gene therapy are discussed in detail in this review. Despite the existence of several major obstacles to making it practical and effective, gene therapy could provide a new strategy for treatment of the traumatically injured brain.

Potential new methods for antiepileptic drug delivery

Use of novel drug delivery methods could enhance the efficacy and reduce the toxicity of antiepileptic drugs (AEDs). Slow-release oral forms of medication or depot drugs such as skin patches might improve compliance and therefore seizure control. In emergency situations, administration via rectal, nasal or buccal mucosa can deliver the drug more quickly than can oral administration. Slow-release oral forms and rectal forms of AEDs are already approved for use, nasal and buccal administration is currently off-label and skin patches for AEDs are an attractive but currently hypothetical option. Therapies under development may result in the delivery of AEDs directly to the regions of the brain involved in seizures. Experimental protocols are underway to allow continuous infusion of potent excitatory amino acid antagonists into the CSF. In experiments with animal models of epilepsy, AEDs have been delivered successfully to seizure foci in the brain by programmed infusion pumps, acting in response to computerised EEG seizure detection. Inactive prodrugs can be given systemically and activated at the site of the seizure focus by locally released compounds. One such drug under development is DP-VPA (or DP16), which is cleaved to valproic acid (sodium valproate) by phospholipases at the seizure focus. Liposomes and nanoparticles are engineered micro-reservoirs of a drug, with attached antibodies or receptor-specific binding agents designed to target the particles to a specific region of the body. Liposomes in theory could deliver a high concentration of an AED to a seizure focus. Penetration of the blood-brain barrier can be accomplished by linking large particles to iron transferrin or biological toxins that can cross the barrier. In the near future, it is likely that cell transplants that generate neurotransmitters and neuromodulators will accomplish renewable endogenous drug delivery. However, the survival and viability of transplanted cells have yet to be demonstrated in the clinical setting. Gene therapy also may play a role in local drug delivery with the use of adenovirus, adeno-associated virus, herpesvirus or other delivery vectors to induce brain cells to produce local modulatory substances. New delivery systems should significantly improve the therapeutic/toxic ratio of AEDs.

Reduced inflammatory reactions to the inoculation of helper-dependent adenoviral vectors in traumatically injured rat brain

Traumatic brain injury (TBI) causes delayed neuronal deficits that in principle could be prevented by timely intervention with therapeutic genes. However, appropriate vectors for gene transfer to the brain with TBI remain to be developed. First-generation adenoviruses (fgAd) are usually associated with inflammatory and toxic effects when inoculated into brains, despite their high efficiency of gene transfer to these tissues. In this study the authors attempted to determine whether a less immunogenic gene-transfer protocol can be established in the traumatically injured rat brain using helper-dependent adenoviruses (hdAd), a novel adenoviral construct with full deletion of viral coding sequences. Their results show that transgene expression from intrahippocampally inoculated hdAd is maintained for at least 2 months after TBI, in contrast to the much shorter duration of fgAd-mediated gene expression. There was only minimal secretion of proinflammatory IL-1beta and TNF-alpha after inoculation of hdAd. Furthermore, the hdAd-mediated gene expression was associated with less microglial proliferation, astrocytic activation, and macrophage infiltration than observed in fgAd-inoculated brains. There was no additional tissue loss after hdAd inoculation compared with PBS injection. Although both anti-adenoviral and neutralizing antibodies were found in serum after brain inoculation of hdAd, they did not appear to affect transgene expression. The results suggest that hdAd are less immunogenic vectors than conventional adenoviral vectors, and offer improved vehicles for long-term therapeutic transgene transfer to traumatically injured brains.