Iranian Journal of Veterinary Surgery

Iranian Journal of Veterinary Surgery

Chitosan-Mediated Metformin Delivery Promotes Dose-Dependent Functional Recovery in a Rat Spinal Cord Injury Model

Document Type : Original Article

Authors
Erfan Sheikh-Akbarizadeh 1
Ahmad Asghari 1
Gholamreza Abedi Cham-Heydari 1
Pejman Mortazavi 2
1 Department of Veterinary Clinical Sciences, SR.C., Islamic Azad University, Tehran, Iran.
2 Department of Pathobiology, SR.C., Islamic Azad University, Tehran, Iran.
10.30500/ivsa.2025.528959.1451
Abstract
Spinal cord injury (SCI) is a severe condition characterized by primary mechanical damage followed by secondary injury mechanisms, which worsen cellular dysfunction and death. Current treatment strategies remain insufficient in mitigating the full consequences of SCI. Metformin (Met) has demonstrated neuroprotective effects in the central nervous system (CNS), raising interest in its therapeutic potential for SCI. However, whether a chitosan (CH) hydrogel loaded with Met can enhance functional recovery after SCI remains unclear. Wistar rats were divided into five groups: a sham group, an SCI group (negative control, NC), and three groups receiving CH hydrogel containing 10, 50, and 100 mg/kg of Met. Behavioral assessments, including locomotor scoring and sensorimotor function tests, demonstrated that sustained delivery of the metformin-chitosan hydrogel significantly enhanced functional recovery in spinal cord-injured rats compared to untreated controls. Quantitative analysis revealed notable improvements in hindlimb coordination, weight-bearing capacity, and reflex responses, suggesting partial restoration of neural circuitry. Furthermore, the CH/Met hydrogel group exhibited accelerated recovery kinetics, with earlier onset of motor improvements relative to standard treatments. These findings collectively supported the therapeutic efficacy of CH/Met hydrogel in mitigating SCI-related deficits, potentially through its combined neuroprotective and regenerative mechanisms.
Keywords
Spinal cord injury
Metformin
Chitosan
Behavioral assessment

Subjects

  1. Freyermuth-Trujillo X, Segura-Uribe JJ, Salgado-Ceballos H, Orozco-Barrios CE, Coyoy-Salgado A. Inflammation: a target for treatment in spinal cord injury. Cells. 2022; 11(17): 2692. doi: 10.3390/cells11172692
  2. Shank CD, Walters BC, Hadley MN. Management of acute traumatic spinal cord injuries. Handbook of Clinical Neurology. 2017; 140:275-298. doi: 10.1016/B978-0-444-63600-3.00015-5.
  3. Hayta E, Elden H. Acute spinal cord injury: A review of pathophysiology and potential of non-steroidal anti-inflammatory drugs for pharmacological intervention. Journal of Chemical Neuroanatomy. 2018; 87: 25-31. doi: 10.1016/j.jchemneu.2017.08.001
  4. Patek M, Stewart M. Spinal cord injury. Anaesthesia and Intensive Care. 2020; 21(8): 411-416. doi: 10.1016/j.mpaic.2023.04.006
  5. Mehar N, Parvez S. Role of melatonin in traumatic brain injury and spinal cord injury. The Scientific World Journal. 2014; 586270. doi: 10.1155/2014/586270
  6. Wang Y, Wang Z, Lu W, Hu Y. Review on chitosan-based antibacterial hydrogels: preparation, mechanisms, and applications. International Journal of Biological Macromolecules. 2024; 255: 128080. doi: 10.1016/j.ijbiomac.2023.128080
  7. Pakulska MM, Ballios BG, Shoichet MS. Injectable hydrogels for central nervous system therapy. Biomedical Materials. 2012; 7(2): 024101. doi: 10.1088/1748-6041/7/2/024101
  8. Shariatinia Z, Jalali AM. Chitosan-based hydrogels: preparation, properties and applications. International Journal of Biological Macromolecules. 2018; 115: 194–220. doi: 10.1016/j.ijbiomac.2018.04.034
  9. Aranaz I, Alcántara AR, Civera MC, Arias C, Elorza B, Heras Caballero A, Acosta N. Chitosan: an overview of its properties and applications. Polymers. 2021; 13(19), 3256. doi: 10.3390/polym13193256
  10. Khattak S, Wahid F, Liu LP, Jia SR, Chu LQ, Xie YY, Li ZX, Zhong C. Applications of cellulose and chitin/chitosan derivatives and composites as antibacterial materials: current state and perspectives. Applied Microbiology and Biotechnology. 2019; 103(5): 1989-2006. doi: 10.1007/s00253-018-09602-0
  11. Bailey CJ, Day C. Metformin: its botanical background. Practical Diabetes International. 2004; 21(3): 115-117. doi: 10.1002/pdi.606
  12. Dadwal P, Mahmud N, Sinai L, Azimi A, Fatt M, Wondisford FE, Miller FD, Morshead CM. Activating endogenous neural precursor cells using metformin leads to neural repair and functional recovery in a model of childhood brain injury. Stem Cell Reports. 2015; 5(2): 166-173. doi: 10.1016/j.stemcr.2015.06.011
  13. Kosaraju J, Seegobin M, Gouveia A, Syal C, Sarma SN, Lu KJ, Ilin J, He L, Wondisford FE, Lagace D, De Repentigny Y, Kothary R, Wang J. Metformin promotes CNS remyelination and improves social interaction following focal demyelination through CBP Ser436 phosphorylation. Experimental Neurology. 2020; 334(2020): 113454. doi: 10.1016/j.expneurol.2020.113454
  14. Ruddy RM, Adams KV, Morshead CM. Age- and sex-dependent effects of metformin on neural precursor cells and cognitive recovery in a model of neonatal stroke. Science Advances. 2019; 5(9): eaax1912. doi: 10.1126/sciadv.aax1912
  15. Tao L, Li D, Liu H, Jiang F, Xu Y, Cao Y, Gao R, Chen G. Neuroprotective effects of metformin on traumatic brain injury in rats associated with NF-κB and MAPK signaling pathway. Brain Research Bulletin. 2018; 140: 154-161. doi: 10.1016/j.brainresbull.2018.04.008
  16. Bourget C, Adams KV, Morshead CM. Reduced microglia activation following metformin administration or microglia ablation is sufficient to prevent functional deficits in a mouse model of neonatal stroke. Journal of Neuroinflammation. 2022; 19(1): 146. doi: 10.1186/s12974-022-02487-x
  17. Wang J, Gallagher D, DeVito LM, Cancino GI, Tsui D, He L, Keller GM, Frankland PW, Kaplan DR, Miller FD. Metformin activates an atypical PKC-CBP pathway to promote neurogenesis and enhance spatial memory formation. Cell Stem Cell. 2012; 11(1): 23-35. doi: 10.1016/j.stem.2012.03.016
  18. Ayoub R, Ruddy RM, Cox E, Oyefiade A, Derkach D, Laughlin S, Ades-Aron B, Shirzadi Z, Fieremans E, MacIntosh BJ, de Medeiros CB, Skocic J, Bouffet E, Miller FD, Morshead CM, Mabbott DJ. Assessment of cognitive and neural recovery in survivors of pediatric brain tumors in a pilot clinical trial using metformin. Nature Medicine. 2020; 26(8): 1285-1294. doi: 10.1038/s41591-020-0985-2
  19. Livingston JM, Syeda T, Christie T, Gilbert EAB, Morshead CM. Subacute metformin treatment reduces inflammation and improves functional outcome following neonatal hypoxia ischemia. Brain, Behavior, and Immunity - Health. 2020; 7: 100119. doi: 10.1016/j.bbih.2020.100119
  20. Zhou Z, Liu Y, Jiang X, Zheng C, Luo W, Xiang X, Qi X, Shen J. Metformin modified chitosan as a multi-functional adjuvant to enhance cisplatin-based tumor chemotherapy efficacy. International Journal of Biological Macromolecules. 2023; 224: 797-809. doi.org/10.1016/j.ijbiomac.2022.10.167
  21. Kaczmarek-Szczepańska B, Ostrowska J, Kozłowska J, Szota Z, Brożyna AA, Dreier R, Reiter RJ, Slominski AT, Steinbrink K, Kleszczyński K. Evaluation of polymeric matrix loaded with melatonin for wound dressing. International Journal of Molecular Sciences. 2021; 22(11): 5658. doi: 10.3390/ijms22115658
  22. Yuan Y, Fan X, Guo Z, Zhou Z, Gao W. Metformin protects against spinal cord injury and cell pyroptosis via AMPK/NLRP3 inflammasome pathway. Analytical Cellular Pathology. 2022; 3634908. doi: 10.1155/2022/3634908
  23. Basso DM, Beattie MS, Bresnahan JC. A sensitive and reliable locomotor rating scale for open field testing in rats. Journal of Neurotrauma. 1995; 12(1): 1-21. doi: 10.1089/neu.1995.12.1
  24. Cai M, Chen L, Wang T, Liang Y, Zhao J, Zhang X, Li Z, Wu H. Hydrogel scaffolds in the treatment of spinal cord injury: a review. Frontiers in Neuroscience, 2023; 17: 1211066. doi: 10.3389/fnins.2023.1211066
  25. Karsy M, Hawryluk G. Modern medical management of spinal cord injury. Current Neurology and Neuroscience Reports. 2019; 19(9): 65. doi: 10.1007/s11910-019-0984-1
  26. Ge A, Wang S, Miao B, Yan M. Effects of metformin on the expression of AMPK and STAT3 in the spinal dorsal horn of rats with neuropathic pain. Molecular Medicine Reports. 2018; 17(4): 5229-5237. doi: 10.3892/mmr.2018.8541
  27. Inyang KE, Szabo-Pardi T, Wentworth E, McDougal TA, Dussor G, Burton MD, Price TJ. The antidiabetic drug metformin prevents and reverses neuropathic pain and spinal cord microglial activation in male but not female mice. Pharmacological Research. 2019; 139: 1-16. doi: 10.1016/j.phrs.2018.10.027
  28. Wang C, Liu C, Gao K, Zhao H, Zhou Z, Shen Z, Guo Y, Li Z, Yao T, Mei X. Metformin preconditioning provide neuroprotection through enhancement of autophagy and suppression of inflammation and apoptosis after spinal cord injury. Biochemical and Biophysical Research Communications. 2016; 477(4): 534-540. doi: 10.1016/j.bbrc.2016.05.148
  29. Zhang D, Xuan J, Zheng BB, Zhou YL, Lin Y, Wu YS, Zhou YF, Huang YX, Wang Q, Shen LY, Mao C, Wu Y, Wang XY, Tian NF, Xu HZ, Zhang XL. Metformin improves functional recovery after spinal cord injury via autophagy flux stimulation Molecular Neurobiology. 2017; 54(5): 3327-3341. doi: 10.1007/ s12035-016-9895-1
  30. Guo Y, Wang F, Li H, Liang H, Li Y, Gao Z, He X. Metformin protects against spinal cord injury by regulating autophagy via the mTOR signaling pathway. Neurochemical Research. 2018; 43(5): 1111-1117. doi: 10.1007/ s11064-018-2525-8
  31. Song WY, Ding H, Dunn T, Gao JL, Labastida JA, Schlagal C, Ning GZ, Feng SQ, Wu P. Low-dose metformin treatment in the subacute phase improves the locomotor function of a mouse model of spinal cord injury. Neural Regeneration Research. 2021; 16(11): 2234. doi: 10.4103/1673-5374.310695
  32. Zhang T, Wang F, Li K, Lv C, Gao K, Lv C. Therapeutic effect of metformin on inflammation and apoptosis after spinal cord injury in rats through the Wnt/β catenin signaling pathway. Neuroscience Letters. 2020; 739: 135440. doi: 10.1016/j.neulet.2020.135440
  33. Wang H, Zheng Z, Han W, Yuan Y, Li Y, Zhou K, Wang Q, Xie L, Xu K, Zhang H, Xu H, Wu Y, Xiao J. Metformin promotes axon regeneration after spinal cord injury through inhibiting oxidative stress and stabilizing microtubule. Oxidative Medicine and Cellular Longevity. 2020; 20. doi: 10.1155/2020/9741369.9741369
  34. Chen Q, Xie D, Yao Q, Yang L. Effect of metformin on locomotor function recovery in rat spinal cord injury model: a meta-analysis. Oxidative Medicine and Cellular Longevity. 2021; 1948003. doi: 10.1155/2021/1948003
  35. Emily A B Gilbert, Jessica Livingston, Emilio Garcia-Flores, Tarlan Kehtari, Cindi M Morshead, Metformin improves functional outcomes, activates neural precursor cells, and modulates microglia in a sex-dependent manner after spinal cord injury, Stem Cells Translational Medicine., 2023; 12(6): 415–428. doi: 10.1093/stcltm/szad030

  • Receive Date 07 June 2025
  • Revise Date 13 July 2025
  • Accept Date 02 August 2025
  • First Publish Date 02 August 2025