EXPERIMENTAL AND CLINICAL TRANSPLANTATION

Objectives: This study aimed to show the positive effects of autologous bone marrow-derived mono-nuclear cells in the functional recovery of adult patients with subacute and chronic ischemic stroke. Stroke is a leading cause of morbidity and long-term disability in the world, with about one-third of survivors being permanently disabled. Bone marrow-derived mononuclear cell concentrate is thought to improve cerebral blood flow and to speed recovery in animal models. Many types of stem cells have been used, including mesenchymal, cord blood cells, and embryonic, with different administration methods, including intrathecal, intravenous, intra-arterial, and intracerebral, all with variable degrees of success. Mechanisms of action include induction of angio-genesis, promotion of neurogenesis, pre-vention of apoptosis, and immunomodulation. The use of autologous bone marrow-derived mononuclear cells with the closed method has nearly minimal manipulation requirements and is a low-risk pro-cedure.

Materials and Methods: We aspirated 100 cm³ (mean volume) of bone marrow from 37 (12 women/25 men) Iraqi adult patients (age range, 42-80 y). After filtration, we injected a small volume (15 cm³) intra-arterially through a catheter in the internal carotid arteries. The remaining volume was injected intrav-enously. Mononuclear cell count was 5 to 6 × 10⁸ per product. Time from diagnosis until transplant procedure ranged from 3 months to 5 years.

Results: Intra-arterial administration of autologous bone marrow mononuclear cells resulted in impro-vements in the European Stroke Scale (from +4 to 20) in 25 of 37 patients (67.5%) over 4 to 8 weeks.

Conclusions: Stem cell therapy is promising in subacute and chronic stroke patients.

Key words : Cerebral blood flow, Cerebral ischemia, Stem cell therapy

Stroke is one of the leading causes of morbidity and long-term disability in the world, with about one-third of survivors becoming permanently disabled. In the early phases of stroke, thrombolytic therapy and endovascular thrombectomy may reduce overall disability; however, options are minimal for recovery once the neurologic deficits have been established.¹

In recent years, extensive cell therapy preclinical research has demonstrated a neurorestorative effect after cerebral ischemia, which showed improved neurologic outcomes even in the long term. The most promising cell therapy is the use of bone marrow mononuclear cells, which have consistently demon-strated efficacy in animal stroke models in different laboratories and species. These cells have the advantage of being rapidly and easily extracted from bone marrow, without cultivation and with minimal manipulation. Because these cells can be injected within 1 hour from bone marrow aspiration, they are suited for autologous administration at any stage of stroke. In addition, the risk of malignant trans-formation and chances of contamination are reduced with autologous minimal manipulation procedures.^2,3

Some preliminary trials have recently shown the safety and feasibility of autologous bone marrow transplant in stroke patients. However, many questions regarding dose, route, and type of cells need to be addressed before starting phase III trials.⁴

In addition to bone marrow mononuclear cell, many other kinds of stem cells have been tested in clinical trials, including autologous mesenchymal stem cells, allogeneic mesenchymal-derived stem cells, autologous peripheral blood stem cells, allogeneic teratocarcinoma-derived neuronal cells, cord blood stem cells, and fetal porcine-derived neural stem cells. These cells have multiple mechanisms of action, including induction of angiogenesis, promotion of neurogenesis, prevention of apoptosis, and immuno-modulation.^5-9

Compared with intravenous administration of mesenchymal stem cells, injection of bone marrow mononuclear cells is expected to have a lower risk of pulmonary embolism because of its smaller cell size.^10,11

In this study, the effects of combined intra-arterial and intravenous administration of autologous bone marrow mononuclear cells were examined in treatment and recovery of patients with chronic stroke.

Materials and Methods

Patient characteristics and selection
Patient selection was based on the World Medical Association Declaration of Helsinki and in accor-dance with the Iraqi guidelines for stem cell therapy. This study was approved by our health ministry ethical committee and by a higher national committee for regenerative medicine. Intervention was performed after written informed consent was given by all patients and/or their relatives in cases when higher mental functions had been affected.¹²

In this single-arm clinical study, 37 consecutive, eligible, and consenting patients were included. Patients (12 women/25 men) ranged in age from 42 to 80 years. Inclusion criteria were patients with chronic ischemic stroke involving the anterior circulation at 3 months to 5 years after onset of stroke.

Product preparation and infusion
Bone marrow aspiration was done under local anesthesia with or without sedation, depending on the individual case. Around 100 mL of bone marrow were aspirated from the posterior iliac crest after proper sterilization using a bone marrow aspiration needle (size according to the patient). Heparinized syringes were used for collection. Mononuclear cells were obtained by filtration. The isolated mono-nuclear cells were checked for viability manually and confirmed with the use of a cell count machine.

Separated mononuclear cells (total cell count range of 5-6 × 10⁸) were administered immediately after filtration. Mononuclear cell products were infused into the antecubital vein (average of 35 cm³). A small volume (average of 15 cm³) was given by catheter to both internal carotid arteries.

We used the European Stroke Scale to assess clinical response to treatment.13 Outcomes measured for safety included immediate reactions after cell infusion and evidence of tumor formation at 6 months to 1 year. Patients were followed monthly after the procedure for 1 year to determine clinical progress using the European Stroke Scale.

Follow-up
Patients were monitored regularly for any immediate adverse effects in the hospital for 3 days after cell therapy. Patients were advised to have follow-up every month. During each follow-up, patients underwent complete neurologic assessment and were monitored for any long-term adverse effects. Patients were followed for a minimum of 6 months.

All 37 patients underwent autologous bone marrow mononuclear cell injection intra-arterially and intravenously. Mononuclear cell counts ranged from 5 to 6 × 10⁸ per product with 97% viability.

Two patients had mild fever 24 hours after infusion, which responded to simple antipyretics. None of the patients had serious adverse events. Of 37 patients, 25 (67.5%) showed improvements in neurological status with increase in European Stroke Scale from 4 to 20.

Time from performing the procedure until showing improvement ranged from 4 to 16 weeks after autologous bone marrow mononuclear cell infusion. Some patients (n = 3) showed marked improvements in speech; in 4 weeks, they were able to speak 1 or 2 words. Others (n = 22) showed improved motor function after neurorehabilitation, which markedly increased the European Stroke Score.

Stem cell therapy has been shown to improve functional status in many neurologic diseases, including cerebral palsy, mental retardation, spinal cord injury, and stroke. A number of trials have demonstrated clinical safety of autologous bone marrow mononuclear cell transplant and even autologous bone marrow-derived mesenchymal stem cell transplant in cases of brain stroke.^14,15 In a multicenter study, the positive effects of intra-venously administered bone marrow mononuclear cells were clear in patients with ischemic stroke.¹⁶

Two issues require clarification. First, if improve-ments occur in patients with chronic ischemic stroke, then we do not believe that there are any other factors that contribute to the improvement if it occurs. This is in contrast to patients with acute or subacute disease, where natural recovery can be a factor. In this study, 67.5% of patients showed improvements. The second important issue is method of bone marrow-derived mononuclear cell administration. Logically, an intra-arterial route would be better in terms of clinical outcome, as more cell count is available at the site of the lesion; however, one study showed no clear differences between the 2 routes of administration.^17,18 Here, we showed that our high clinical response rate (67.5%) may be due to intra-arterial injection.

The improvements seen here can be explained by the physiological processes occurring at the micro-cellular level in the brain as a result of cell therapy, which is exerted by bone marrow cells. These processes (angiogenesis, neovascularization, produc-tion of growth factors, and paracrine effects) lead to increased synaptic plasticity at the penumbral area in the brain. In addition, bone marrow stem cells are multipotent and can differentiate into different tissue types, including astrocytes, neurons, and endothelial cells in the brain.¹⁹

With regard to safety, because our procedure was autologous, use of these cells does not hold the risk of graft-versus-host disease or tumors. Future studies will determine the best route and type of cells to be used in patients with chronic ischemic stroke.

Volume: 17 Issue: 1 January 2019 - Supplement - 1

FULL TEXT