NT3P75-2 gene-modified bone mesenchymal stem cells improve neurological function recovery in mouse TBI model

Abstract

Background: The attainment of extensive neurological function recovery remains the key challenge for the treatment of traumatic brain injury (TBI). Transplantation of bone marrow-derived mesenchymal stem cells (BMSCs) has been shown to improve neurological function recovery after TBI. However, the survival of BMSCs after transplantation in early-stage TBI is limited, and much is unknown about the mechanisms mediating this neurological function recovery. Secretion of neurotrophic factors, including neurotrophin 3 (NT3), is one of the critical factors mediating BMSC neurological function recovery. Gene mutation of NT3 (NT3 P75-2) has been shown to enhance the biological function of NT3 via the reduction of the activation of the P75 signal pathway. Thus, we investigated whether NT3 P75-2 gene-modified BMSCs could enhance the survival of BMSCs and further improve neurological function recovery after TBI. Methods: The ability of NT3 P75-2 induction to improve cell growth rate of NSC-34 and PC12 cells in vitro was first determined. BMSCs were then infected with three different lentiviruses (green fluorescent protein (GFP), GFP-NT3, or GFP-NT3 P75-2), which stably express GFP, GFP-NT3, or GFP-NT3 P75-2. At 24 h post-TBI induction in mice, GFPlabeled BMSCs were locally transplanted into the lesion site. Immunofluorescence and histopathology were performed at 1, 3, and/or 7 days after transplantation to evaluate the survival of BMSCs as well as the lesion volume. A modified neurological severity scoring system and the rotarod test were chosen to evaluate the functional recovery of the mice. Cell growth rate, glial activation, and signaling pathway analyses were performed to determine the potential mechanisms of NT3 P75-2 in functional recovery after TBI. Results: Overall, NT3 P75-2 improved cell growth rate of NSC-34 and PC12 cells in vitro. In addition, NT3 P75-2 significantly improved the survival of transplanted BMSCs and neurological function recovery after TBI. Overexpression of NT3 P75-2 led to a significant reduction in the activation of glial cells, brain water content, and brain lesion volume after TBI. This was associated with a reduced activation of the p75 neurotrophin receptor (P75NTR) and the c-Jun N-terminal kinase (JNK) signal pathway due to the low affinity of NT3 P75-2 for the receptor. Conclusions: Taken together, our results demonstrate that administration of NT3 P75-2 gene-modified BMSCs dramatically improves neurological function recovery after TBI by increasing the survival of BMSCs and ameliorating the inflammatory environment, providing a new promising treatment strategy for TBI.

Human Umbilical Cord–Derived Mesenchymal Stem Cell Therapy Effectively Protected the Brain Architecture and Neurological Function in Rat After Acute Traumatic Brain Injury

“…Second, the early time point of brain MRI was not performed as a “reference image” for comparison among the groups after TBI procedure and the effect of TBI and UCDMSCs transplantation on rodent memory was not assessed in the present study. Third, the dosage of HUCDMSC to be utilized in the present study was simply based on our previous studies 14 , 15 without testing the efficacy of applying different dosages. Accordingly, this study was void of providing the optimal dosage of HUCDMSC for TBI therapy in rodent.…”

“…The potential therapeutic mechanisms comprise replacement of damaged neural cells, promotion of endogenous neural cells, secretion of neurotrophic factors, induction of vascularization and angiogenesis, reduction of apoptosis, and prevention of inflammatory effect 13 . However, the majority of MSC sources for TBI are derived from autologous or allogenic tissues which, therefore, cannot answer how reliable the immune privilege of the MSCs is 14 , 15 . Additionally, genetic manipulation of the MSC prior to implantation has frequently used in reported studies thus raising another serious issue of tumorigenesis formation 14 , 15 .…”

“…However, the majority of MSC sources for TBI are derived from autologous or allogenic tissues which, therefore, cannot answer how reliable the immune privilege of the MSCs is 14 , 15 . Additionally, genetic manipulation of the MSC prior to implantation has frequently used in reported studies thus raising another serious issue of tumorigenesis formation 14 , 15 . These aforementioned issues show that xenogeneic source of HUCDMSC therapy for animals after TBI may provide stronger evidence to answer the above two concerns.…”

Potential of mesenchymal stem cells alone, or in combination, to treat traumatic brain injury

“…Other investigators have focused on the neurotrophins. Wu and associates overexpressed NT3 in MSCs and observed decreased glial activation, a smaller brain lesion, and decreased edema in the brain, while a number of investigators have focused on increasing BDNF expression in the cells, essentially improving functional outcome …”

Transplanting Rac1-silenced bone marrow mesenchymal stem cells promote neurological function recovery in TBI mice

“…Unfortunately, owing to the hostile perilesional microenvironment caused by hypoxic-ischemia, oxidative stress, and inflammation post-TBI [ 13 ], nearly 99% of transplanted cells fail to thrive [ 14 ]. To improve BMMSCs survival rate therefore, some studies have subjected to various degrees of genetic modification [ 15 ] and hypoxic pre-conditioning [ 16 ]. Nevertheless, there are still some limitations that warrant attention into newer methods to promote BMMSCs survival and curative effect.…”