Abstract
Waloschková E, Melin E, Baumlin C, Andersson M, Serrano AM, Kokaia M, Ledri M. Modulation of epileptogenesis through transplantation of human mesenchymal stem cells with or without GDNF release. Cell Mol Life Sci. 2025 Aug 21;82(1):316. doi: 10.1007/s00018-025-05853-z. PMID: 40839114; PMCID: PMC12370614. Epilepsy is a central nervous system disorder causing uncontrollable seizures. One-third of patients do not respond to current medications, necessitating new treatments. This study targeted epileptogenesis, the process leading to chronic epilepsy, using human mesenchymal stem cells (MSCs) in a rodent model. MSC transplantation can positively affect neurodegenerative diseases by modifying inflammation. Additionally, glial cell line-derived neurotrophic factor (GDNF) may counteract seizures and tissue damage. We transplanted naïve immortalized human adipose-derived MSCs (Ctrl-MSCs) or GDNF-releasing MSCs (GDNF-MSCs, releasing 588.67 ± 20.14 pg/ml/24 h GDNF) into rat hippocampi after kainic acid-induced status epilepticus. Seizure progression was monitored for 5 weeks using video-EEG, behavioral assessments, and histological analysis. Both cell types influenced epileptogenesis. GDNF-MSCs delayed early-stage seizures, while Ctrl-MSCs reduced seizure frequency in later stages. Differences emerged in seizure development and cumulative seizure count, with Ctrl-MSCs showing significant seizure-attenuating effects. Behavioral differences were also noted: Ctrl-MSCs improved short-term memory and reduced anxiety, whereas GDNF-MSCs primarily reduced anxiety without significantly improving memory. This study highlights the therapeutic potential of MSCs, with or without GDNF, in modulating epileptogenesis, offering promising avenues for future clinical treatments.
Commentary
The transplantation of stem cells via peripheral administration, intrathecally or directly into an identified seizure focus is currently being investigated experimentally and clinically to prevent or treat seizures. Stem cells have the potential to replace damaged cells, prevent neurodegeneration, interfere with aberrant synaptic reorganization and suppress neuroinflammation. 1 The different types of stem cells, classified by their tissue of origin, include mesenchymal stem cell (MSC), derived from bone or adipose tissue, neural, embryonic and induced pluripotent stem cells. 2 MSC can migrate into areas of damage and exert their antiepileptic actions primarily through the paracrine release of neurotrophic factors2,3 while other types of stem cells have the potential to differentiate into neurons and glial cells, distribute throughout the implanted structure and in the case of neurons make and receive functional synaptic connections. 4 Experimentally, intrahippocampal injections of GABAergic progenitor cells, derived from the medial ganglionic eminence 4 and embryonic neural stem cells (NSCs) collected from the embryonic rat hippocampus 5 both decreased the frequency of spontaneous recurrent seizures (SRS) in rodent models of status epilepticus (SE). Similar results have been reported with MSCs administered peripherally, intraventricularly and directly into the hippocampus in several seizure models. 6
The highlighted study focused on the ability of transplanted human immortalized adipose-derived MSCs to interfere with epileptogenesis using the rat kainic acid (KA) model of SE. 7 SE was induced by injecting multiple doses of KA into male Sprague-Dawley rats until the first Stage 3 or greater behavioral seizure was observed using the Racine scale. Each animal then received bilateral hippocampal injections with 1 of 2 MSC lines: control MSC (Ctrl-MSC) or MSC genetically engineered to released glial cell-derived neurotrophic factor (GDNF-MSC), 16-24 h after SE induction. Sham animals were injected with KA but did not receive stem cell therapy. GDNF-MSC treated animals were included in the study due to evidence that treatment with GDNF delayed seizure onset, reduced seizure number and reduced neurodegeneration.8,9 Before transplantation both populations of stem cells were transduced with lentivirus containing mCherry to allow for later histological verification of the localization and survival of the cells after transplantation. Control experiments were performed to ensure that both types of MSCs expressed mCherry, and that the GDNF-MSCs released GDNF. EEG electrodes were implanted at the time of stem cell implantation to allow for 35 days of continuous video-EEG monitoring. To assess the survival and localization of both types of MSCs, tissue from each group was collected 7, 14, and 21 days after MSC transplantation for histological analysis. Behavioral testing for anxiety, novel object recognition and locomotion was performed after the 35 days of video-EEG monitoring. Histological analysis revealed that both Ctrl-MSC and GDNF-MSCs were present 7 and 14 days after implantation but were not present on day 21 indicating they did not survive throughout the 35 days of video-EEG monitoring and behavioral testing.
During video-EEG monitoring some animals in each of the 3 groups failed to exhibit a seizure, with significantly fewer Ctrl-MSC treated animals exhibiting seizures than sham controls. A similar effect was not observed in the GDNF-MSC treated animals. When seizures did occur, most originated in the hippocampus. Stem cell therapy had no effect on the latency to the first seizure. While both types of stem cells affected epileptogenesis, treatment with GDNF-MSCs decreased the probability of a seizure occurring during the first 2 weeks after SE, while treatment with Ctrl-MSCs significantly decreased seizure frequency during the last 3 weeks of video-EEG monitoring. However, there was no difference in overall seizure frequency during the 35 days of recording between the stem cell–treated groups and sham controls. There was also no difference in seizure duration, or the total time spent seizing. A significant number of Ctrl-MSC-treated animals exhibited a seizure frequency that was more than 50% less than the median seizure frequency observed in the sham controls. Another positive effect of treatment with GDNF-MSCs was a significant increase in the interval between seizures even though there was no significant difference in the total number of seizures. An assessment of the effect of MSC therapy on epilepsy-related behavioral deficits revealed that treatment with both types of stem cells significantly reduced anxiety assessed with the open field test, however only treatment with Ctrl-MSCs resulted in a significant improvement in short-term memory assessed using the novel object recognition test. Early intervention with either type of MSC had no effect on microglial activation, suggesting there was no effect on SE-induced inflammation.
Compared to other experimental studies that examined the feasibility and efficacy of stem cell therapy to treat epilepsy, this study is somewhat unique in that it focused on epileptogenesis, and it utilized human immortalized adipose-derived mesenchymal stem cells (HiAD-MSC). A demonstration of efficacy with HiAD-MSC is more easily translatable to clinical use because it raises the potential of using the patient's own autologous stem cells, reducing the likelihood of rejection. It is unfortunate that in this study both types of MSCs did not survive the duration of the experiment because it raises questions of why and how they affected seizures, behavior, and inflammation. The lack of survival also limits the potential for translation if the transplanted cells do not maintain a long-term presence at the focus. It was also surprising that the use of GDNF-MSC, designed to release GDNF into the focus, did not result in more significant changes in seizure activity given the positive results reported in previous studies when GDNF was delivered by itself.8,9
Clinically stem cell therapy for epilepsy is still in its infancy with only a limited number of clinical trials. In a recent randomized, phase one, open label study, patients with drug-resistant epilepsy received autologous bone marrow-derived MSCs treatment delivered through 2 injections, the first intravenously followed 1 week later intrathecally. This was repeated 6 months later. Control patients continued to receive their standard antiseizure medications (ASMs). 10 The MSC treatment was found to be safe with a significant reduction in seizure frequency accompanied by an improvement in paroxysmal EEG activity. Despite these positive results, issues revolving around safety, timing, the types of cells used and where to administer them still need to be resolved. 11 Given the proliferative nature of stem cells there is the potential for malignancy, and it is unclear how the newly introduced stem cells will respond to ASM.1,11 As highlighted in the current study 7 there can be issues with cell survival and retention.
In conclusion, the study by Waloschkova et al 7 provides further evidence of the potential of stem cell therapy for the treatment of epilepsy. Positive effects on epileptogenesis raise the possibility of using stem cell therapy to prevent the development of posttraumatic epilepsy after trauma and stroke. However, the study also highlights some of the hurdles that must be overcome before stem cell therapy can become a viable clinical alternative.
