Here is the design of a clinical trial:

Official Title: Allogeneic Adipose Tissue-derived Mesenchymal Stem Cells in Ischemic Stroke. A Phase IIB Multicenter Double Blind Placebo Controlled Clinical Trial

Included conditions:
- Ischemic Stroke
- Adipose Tissue-derived Stem Cell
- Functional Status

Study Armgroups:
- {'label': 'Treatment group', 'type': 'EXPERIMENTAL', 'description': '15 patients will receive intravenous alogenic adipose tissue-derived stem cells in a single dose of one million cells per kg.', 'interventionNames': ['Other: Alogenic adipose tissue-derived stem cells']}
- {'label': 'Placebo group', 'type': 'PLACEBO_COMPARATOR', 'description': '15 patients will receive a single intravenous placebo solution with the same appearance as the treatment group.', 'interventionNames': ['Drug: Placebo solution']}

Interventions:
- {'type': 'OTHER', 'name': 'Alogenic adipose tissue-derived stem cells', 'description': 'Concentration of the cells: 10 million cells / ml', 'armGroupLabels': ['Treatment group']}
- {'type': 'DRUG', 'name': 'Placebo solution', 'description': 'Placebo intravenous solution, same appearance stem cells solution', 'armGroupLabels': ['Placebo group']}

Primary Outcomes:
- {'measure': 'Safety of administration of adipose tissue-derived mesenchymal stem cells measured as reported adverse events', 'description': 'Adverse events reported spontaneously or in response to questions not addressed.', 'timeFrame': 'Up to 24 months after treatment or placebo administration'}
- {'measure': 'Safety of administration of adipose tissue-derived mesenchymal stem cells measured as neurological o systemic complications', 'description': 'Neurological or systemic complications', 'timeFrame': 'Up to 24 months after treatment or placebo administration'}

Please estimate the sample size based on the assumption: 
No systematic sample size calculation applies.
Sample size estimates
        Given this is a pilot phase II clinical trial focused on the assessment of safety, no systematic sample size calculation applies. Based on the previous clinical trial, AMASCIS-01, it seems feasible to recruit 30 patients between the two participating centres.