Ischemic stroke results from interruption of cerebral blood flow and produces a time-dependent core of irreversible injury surrounded by variably salvageable tissue. MSC and extracellular-vesicle research has focused largely on post-acute repair rather than replacing emergency reperfusion therapy. Proposed mechanisms include immunomodulation, trophic signaling, angiogenic and neurovascular effects, support of endogenous plasticity, and modification of secondary injury. Human trials have used heterogeneous products, routes, doses, and treatment windows, and have not established MSCs or EVs as routine stroke therapy. Any investigational use must remain distinct from proven acute interventions such as thrombolysis or mechanical thrombectomy in eligible patients.
Figure 1 placeholder — Ischemic stroke
Hemorrhagic stroke
Hemorrhagic stroke involves bleeding into or around the brain, with injury from the hematoma, pressure, edema, inflammation, and secondary tissue damage. Its biology differs fundamentally from arterial occlusion, so ischemic-stroke cell-therapy findings cannot be transferred automatically. MSC or EV studies are primarily preclinical or early clinical and investigate modulation of inflammation, edema, vascular injury, and repair. Safety is especially important because intracranial bleeding, mass effect, blood-pressure management, neurosurgical indications, and coagulation status dominate acute care. A plausible neurorepair mechanism does not establish benefit in intracerebral or subarachnoid hemorrhage.
Figure 2 placeholder — Hemorrhagic stroke
Traumatic brain injury
Traumatic brain injury (TBI) ranges from focal contusion to diffuse axonal injury and can produce evolving excitotoxic, inflammatory, vascular, metabolic, and neurodegenerative consequences. MSC and EV research explores immunomodulation, trophic support, vascular stabilization, and neural plasticity. Translation is difficult because injury mechanism, severity, timing, age, rehabilitation, and outcome measures vary substantially. Early human studies cannot be interpreted as proof of neuronal replacement or durable neurologic recovery. Standard neurocritical care, prevention of secondary brain injury, surgery when indicated, and structured rehabilitation remain the clinical foundation.
Figure 3 placeholder — Traumatic brain injury
Spinal-cord injury
Spinal-cord injury causes primary mechanical damage followed by secondary inflammation, ischemia, demyelination, axonal disruption, glial scarring, and loss of neural circuitry. Investigational cell approaches include MSCs as well as other neural or progenitor-cell products, which should not be conflated. Proposed MSC/EV effects are mainly paracrine and immunomodulatory, with possible support of angiogenesis, remyelination, and host repair. Human studies remain heterogeneous in injury level, completeness, chronicity, route, dose, and rehabilitation. Changes in sensory or motor scores require controlled interpretation because spontaneous recovery is strongly time-dependent after injury.
Figure 4 placeholder — Spinal-cord injury
Multiple sclerosis
Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system characterized by inflammatory demyelination, axonal injury, and variable neurodegeneration. MSC research has investigated immunomodulatory and neuroprotective strategies, while hematopoietic stem-cell transplantation is a distinct treatment platform intended to reset immune function in selected patients. These approaches must not be described interchangeably. Small MSC trials have explored safety, imaging, visual, and disability outcomes, but routine efficacy has not been established. Disease-modifying therapies with established indication-specific evidence remain the standard comparator.
Figure 5 placeholder — Multiple sclerosis
Parkinson’s disease
Parkinson’s disease is a progressive neurodegenerative disorder characterized clinically by motor and nonmotor features and pathologically by loss of dopaminergic neurons and broader network dysfunction. MSC or EV approaches are investigational and are conceptually different from dopaminergic neuron replacement strategies using neural progenitor or pluripotent-stem-cell-derived products. Proposed MSC mechanisms include trophic, anti-inflammatory, mitochondrial, and neuroprotective signaling. Preclinical plausibility does not establish restoration of nigrostriatal circuitry or durable clinical benefit. Established symptomatic therapies and appropriately selected device-based treatments remain standard care.
Figure 6 placeholder — Parkinson’s disease
Alzheimer’s disease
Alzheimer’s disease is a progressive neurodegenerative disorder involving amyloid, tau, synaptic dysfunction, neuroinflammation, neuronal loss, and network failure. MSC and EV studies have proposed anti-inflammatory, trophic, proteostatic, and neuroprotective mechanisms, but most evidence remains preclinical or early clinical. Changes in biomarkers do not establish preservation of cognition or function, and intracerebral or intrathecal delivery adds procedure-specific considerations. Disease-modifying anti-amyloid therapies are a separate therapeutic class with their own eligibility, monitoring, and risk profiles. Claims of neuronal regeneration or reversal of established dementia require evidence not supplied by mechanistic rationale alone.
Figure 7 placeholder — Alzheimer’s disease
ALS
Amyotrophic lateral sclerosis (ALS) is a progressive motor-neuron disease with heterogeneous genetic and sporadic forms. Cell-based investigations have included MSC-derived neurotrophic products and other cellular strategies intended primarily to modify the motor-neuron environment rather than replace the entire corticospinal and lower-motor-neuron system. Trials have examined safety, biomarkers, and functional decline, but results do not support a class-wide efficacy claim for MSCs. Disease progression, respiratory function, genotype, phenotype, concomitant therapy, and timing complicate interpretation. Established multidisciplinary ALS care and approved disease-modifying therapies remain essential comparators.
Figure 8 placeholder — ALS
Peripheral neuropathy
Peripheral neuropathy is a broad category that includes diabetic, toxic, immune-mediated, hereditary, ischemic, traumatic, and other disorders of peripheral nerves. A mechanism or clinical signal in one neuropathy cannot be generalized to another. MSC and EV research has explored angiogenic, anti-inflammatory, trophic, and Schwann-cell-supportive effects, particularly in preclinical models. Human evidence is limited and product-specific. Clinical management should first identify and treat the underlying cause, address pain and functional impairment, prevent complications, and use disease-specific immunologic or metabolic therapy when indicated.
Figure 9 placeholder — Peripheral neuropathy
Clinical takeaway
Neurologic conditions differ radically in pathophysiology, natural history, treatment window, and standard care. No class-wide conclusion about MSCs or EVs is scientifically defensible across these nine indications.
Biological rationale
Proposed mechanisms include immunomodulation, neuroprotection, trophic signaling, angiogenesis, modulation of glial responses, support of endogenous plasticity, and extracellular-vesicle signaling. These mechanisms do not by themselves establish neuronal replacement.
Product identity
Autologous and allogeneic MSCs, culture-expanded products, neural progenitors, pluripotent-cell-derived neural products, conditioned media, and EV preparations are distinct interventions. Evidence must remain attached to the tested product.
Preclinical evidence
Animal and laboratory models support multiple neuroprotective and repair hypotheses, but model timing and injury homogeneity often differ sharply from human neurologic disease.
Human clinical evidence
Human development is uneven across indications and generally remains investigational for MSC/EV products. Small samples, uncontrolled designs, variable dosing, and heterogeneous endpoints frequently limit inference.
Trial design
Neurologic trials must account for spontaneous recovery, rehabilitation, placebo and procedural effects, disease progression, baseline severity, rescue treatment, and clinically meaningful functional endpoints.
Dose and administration
Intravenous, intra-arterial, intrathecal, intracerebral, intraspinal, and local delivery are not interchangeable. Route changes biodistribution, invasiveness, dose exposure, and safety.
Safety
Potential risks include infection, inflammatory or immune reactions, thrombo-inflammatory effects, seizures, procedure-related neurologic injury, and product-specific theoretical risks. Invasive CNS delivery adds distinct hazards.
Regulatory status
Regulatory authorization is product-, indication-, route-, and jurisdiction-specific. Trial registration or biologic plausibility is not authorization for routine clinical marketing.
Standard care
Emergency reperfusion for eligible ischemic stroke, neurocritical care, disease-modifying MS therapy, established Parkinson and Alzheimer therapies, multidisciplinary ALS care, and cause-directed neuropathy treatment should not be displaced by investigational cell claims.
Knowledge gaps
Priorities include reproducible product characterization, validated potency assays, dose-response, optimal timing, responder selection, durable functional outcomes, and long-term safety.
Bottom-line evidence statement
Neurologic MSC/EV research is biologically active and clinically investigational; mechanistic promise must remain separate from proof of durable, patient-important neurologic benefit.
Additional controlled terminology
Neuroprotection aims to limit injury, while neuroinflammation and neuroplasticity can influence recovery. Demyelination and remyelination affect axonal conduction; axonal injury and a glial scar can limit circuit recovery. The blood-brain barrier and neurovascular unit shape CNS homeostasis. Excitotoxicity and diffuse axonal injury are important secondary-injury concepts. A motor neuron differs from a dopaminergic neuron of the nigrostriatal pathway. Amyloid and tau are central Alzheimer-related pathologies. A Schwann cell supports peripheral nerves. Intrathecal administration and intracerebral administration are invasive routes with different risks. A functional outcome should be separated from a biomarker, and spontaneous recovery must be considered in acute injury trials.