Table 1 Inclusion and exclusion criteria

Inclusion criteria

-Diagnosis of ’probable Progressive Supranuclear Palsy - Richardson’s disease subtype’ according to current diagnostic criteria [4; 9], including akinetic-rigid syndrome;

-Age at onset ≥ 40 years;

-Disease duration 12 months to 8 years;

-Supranuclear ophthalmoplegia;

-Postural instability or falls within 3 years from disease onset;

-Positive MRI for PSP criteria (Quattrone et al., [30]);

-Stable pharmacological treatment for at least 90 days;

-Lack of response to chronic levodopa (at least 12-month treatment);

-Able to stand in upright posture without assistance for at least 30 seconds;

-Written informed consent (including video taping).

Exclusion criteria

-Idiopathic Parkinson’s disease;

-Cerebellar ataxia;

-Symptomatic autonomic dysfunction;

-Evidence of any other neurological disease that could explain signs;

-History of repeated strokes with stepwise progression of parkinsonian features;

-History of major stroke;

-Any history of severe or repeated head injur;

-A history of encephalitis;

-A history of neuroleptic use for a prolonged period of time or within the past 6 months;

-Street-drug related parkinsonism;

-Significant other neurological disease on CT-scan/MRI;

-Oculogyric crises;

-major signs of corticobasal degeneration;

-Signs of Lewy body disease;

-Other life-threatening disease likely to interfere with the main outcome measure;

-Any clinically significant laboratory abnormality, with the exception of cholesterol, triglycerides and glucose;

-Renal failure (serum creatinine >300 mM/L);

-Transaminase elevation > twice upper limit of normal;

-Any concomitant disorder associated with bone marrow function impairment;

-Any concomitant disorder that requires chronic treatment with immunosuppressors, anti-inflammatory agents, and/or growth factors;

-Dementia (MMSE < 24 according to Folstein 1975 or defined according to DSM-IV TR criteria);

-Any other disorder that could interfere with the evaluation of treatment or that could make intra-arterial infusion inadvisable;

-Any other features that, according to the investigator, could reduce adherence to protocol procedures or prevent rapid access in case of emergency;

-Women of child-bearing age;

-Participation in another clinical trial with experimental treatment in the last 30 days;

-Brain MRI evidence of severe vascular abnormalities, space-occupying lesions or normal pressure hydrocephalus.