Therapeutic potential of mesenchymal stem cells after transplantation in traumatic brain injury mice: an in vivo 1H MRS and behavioural study
Sushanta Kumar Mishra1,2, Subash Khushu1, and Gurudutta Gangenahalli2

1NMR Research Centre, Institute of Nuclear Medicine and Allied Sciences, Delhi, India, 2Division of Stem Cell and Gene Therapy Research, Institute of Nuclear Medicine and Allied Sciences, Delhi, India

Synopsis

Mesenchymal stem cells have been shown to be effective against neuronal degeneration through mechanisms that include both the recovery of neurometabolites and behavioural activity. This study demonstrates that intravenous administration of MSCs in traumatic brain injury mice alter the neurometabolic concentration at lesion site and improve the behavioural functional outcome. The concentrations of metabolites like phosphocholine and inositol were increased, while other metabolites like NAA, GABA, Cr+PCr, Glu+Gln and taurine were decreased at injury site after MSCs transplantation and become its normal concentrations. The functional activities like stress level, grip strength and depression index were improved in transplanted TBI mice.

Introduction

Traumatic brain injury is a broad range of physical, cognitive, behavioural, and emotional impairments that depend on the type, severity and site of the injury1. It is a significant global health problem and leading cause of death and disability. Stem cell transplantation has enormous potential to be a viable therapeutic approach to replace the lost cells following regeneration of tissues2. Localized in vivo 1H MRS of the brain parenchyma provides information on several compounds of interest for monitoring changes in TBI3. Alteration of neurometabolites concentrations in TBI site and its recovery after transplantation became a promising interest. The behavioural improvements as well as recovery of metabolites occur after differentiation of transplanted stem cells at TBI site.

Objectives

To investigate the alteration of neurometabolic concentrations and its behavioural functional outcome in TBI mice after transplantation of MSCs

Materials and Methods

Traumatic brain injury in female mice was carried out by free falling weight drop method. Three experimental groups were considered (8 mice per group): 1. Control, 2. TBI mouse, 3. TBI mouse + stem cells. MSCs were isolated from bone marrow of male Balb/c mice and cultured in DMEM-LG medium with 15% FBS. After 3rd passage, MSCs (1x106 cells in 200 µl PBS) were administered intravenously in tail of TBI mice and in vivo 1H MRS was carried out in 7T Bruker Biospec USR 70/30, (AVANCE III) animal MRI after day 1, 7, 14 and 21. The control and TBI groups were injected with 200 µl of PBS. Localized proton spectra were acquired using a point resolved spectroscopy (PRESS) sequence. The voxel size of 1.5 × 3 × 1.5 mm3 was placed within the region of interest. All spectra were initially processed using Topspin 3.1 software provided on the scanner and raw data were analyzed using LC-model. The LC-model automatically calculates the metabolite concentrations and the uncertainties using Cramér–Rao lower bound (CRLB) formalism. An estimate was considered as relevant when the corresponding bound was found below 20%. Behavioural studies like stress level, grip strength and depression index were carried out on day-21.

Results and Discussions

The MRS spectra of control, TBI and TBI+ stem cells mice were shown in Figure 1. Quantitative analysis demonstrated that metabolites like NAA, GABA, Cr+Pcr, Glu+Gln and taurine were decreased after TBI and other metabolites like inositol and phosphocholine were increased (day-7). After transplantation of MSCs, the metabolites levels were altered and the concentrations came to its normal on day-21(Figure 2). Improvements in behavioural activities were observed stress level, grip strength and depression index (Figure 3). These changes provide evidence of altered cellular metabolic status after TBI, with specific status, bioenergetics, oxidative stress, inflammation and cell membrane disruption. Our results support the utility of 1H-MRS in TBI pathology and its potential approach for preclinical evaluation of novel therapies.

Conclusion

The neurometabolic profile can provide valuable insight into the complex, dynamic responses of the TBI brain. This information may be useful for facilitating translation of novel therapies. Altered cellular metabolic status and improvement in functional behaviour in TBI mice indicates the therapeutic potential of stem cells. This 1H-MRS may be used as a tool and become increasingly valuable for developing novel cellular therapies.

Acknowledgements

The project (INM-311) was financially supported by DRDO, Ministry of Defence, Govt. of India and fellowship supported from ICMR is gratefully acknowledged.

References

1. Harris J L, Yeh H W, Choi I Y et al. Altered neurochemical profile after traumatic brain injury: 1H-MRS biomarkers of pathological mechanisms. Journal of Cerebral blood flow & Metabolism 2012; 32: 2122-2134.

2. Crain B J, Tran S D and Mezey E. Transplanted human bone marrow cells generate new brain cells. Journal of the Neurological Sciences 2005; 233: 121-123.

3. Lescot T, Fulla-Oller L, Po C et al. Temporal and regional changes after focal traumatic brain injury. Journal of Neurotrauma 2010; 27: 85-94.

Figures

Figure 1: Proton magnetic resonance spectra showing major metabolites. A. Control mouse; B. TBI mouse; C. TBI+Stem cells transplanted mouse

Figure 2: Differences in metabolic concentrations as determined by 1H-MRS in control mice, TBI mice and mice treated with stem cells at different time points. (GABA- gamma aminobutyric acid, PCho- phosphocholine, Glu- glutamate, Gln- glutamine, Tau- taurine, NAA- N-acetyl aspertate, Ins-myo-inositol, Cr- creatinine)

Figure 3: Behavioural assessment in control mice, TBI mice and TBI mice treated with stem cells on day-21. A. Stress level; B. Grip strength; C. Depression index assessment.



Proc. Intl. Soc. Mag. Reson. Med. 24 (2016)
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