Stroke is associated with disability and impaired quality of life. Persistent motor impairment is common with incomplete recovery of motor function after rehabilitation, mainly in the upper limbs (UL). Robot-mediated therapy (RMT) has been proposed as a viable approach for the rehabilitation of the UL, but more rigorous studies are needed to tailor rehabilitation and to better address the treatment. Brain-derived neurotrophic factor (BDNF) and the serotonin transporter gene (SLC6A4) have been shown to play an important role in post-stroke recovery. After ischemic stroke, disruption and subsequent reorganization of functional brain connections occur both locally and far from the lesion, with the latter possibly contributing to function recovery.

This project aims to assess whether epigenetic and genetic variations of BDNF and SLC6A4 can occur in stroke patients after robotic rehabilitation treatment.

This study will allow to identify potential genetic and epigenetic biomarkers in post-stroke rehabilitation that could be used to predict the response to a specific rehabilitation treatment and to choose the optimal treatment for the patient (Rehabilomics).

Epigenetic and single-nucleotide polymorphisms (SNPs) in genes may influence an individual's capacity for use-dependent plasticity, and hence their responsiveness to post-stroke rehabilitation. Understanding genetic variation gives clinicians a biological signal that could be used to predict who is most likely to recover from neural injury, to choose the optimal treatment for a patient, or to supplement rehabilitation therapy.

Robotics demonstrated to be an effective rehabilitation treatment for functional and motor recovery after stroke and, on the basis of investigators' preliminary results, it seems to be an useful therapy to improve some cognitive functions. The identification of individual characteristics is crucial factor to better address this treatment and to develop more tailored patients' rehabilitation program.

The characterization of the link between personal biology and rehabilitation treatment response will allow to define a model of Rehabilomics research as a translational framework for programs of precision rehabilitation and intervention research.

In order to identify potential diagnostic and prognostic genetic biomarkers in post-stroke rehabilitation, the investigators will analyze the promoter methylation of BDNF and SLC6A4, two genes implicated in sub-acute stroke recovery. Moreover, the investigators will also detect BDNF rs6265 and SLC6A4 5-HTTLPR polymorphisms.

Subjects will be evaluated at baseline (T0), after 30 sessions of rehabilitation treatment (T1) and, if possible, after other 30 sessions of rehabilitation treatment from T1 (T2).

All patients will perform a robotic treatment of the upper limb (30 sessions, 5 times a week) using a set of robotic devices. Where possible, some patients will undergo further 30 robotic rehabilitation sessions after T1.

Peripheral blood (6ml) will be taken from all subjects at three time points (T0, T1 and T2) during the rehabilitation treatment.

Genomic DNA, obtained from peripheral blood will be analyzed to evaluate promoter methylation of BDNF and SLC6A4 using pyrosequencing analysis with PyroMark Q24 (Qiagen, Germany).

Moreover, BDNF rs6265 polymorphism will be analyzed using HpyCH4IV restriction enzyme which identifies homozygous Valine/Valine, heterozygous Valine/Methionine and homozygous Methionine/Methionine.

For the SLC6A4 5-HTTLPR polymorphism, the investigators will follow a specific protocol that identifies gene polymorphisms according to the polymerase chain reaction (PCR) fragment sizes: short [S; 486 base pairs (bp), 14 repeats], long [L; 529bp, 16 repeats], or extra long [XL; 612 or 654bp, 20 or 22 repeats].

Genetic and epigenetic results will be correlated with:

i) the effects of the robotic rehabilitation on the upper limb function and disability measured with the following clinical scales: Fugl-Meyer Assessment for Upper Extremity (FMA), to evaluate motor function; the Motricity Index (MI), to evaluate muscle strength; the Modified Barthel Index (mBI), to evaluate activities of daily living (ADL) and mobility.

ii) the effects on cognitive functions measured with following cognitive tests: 1) Digit Span (attention/short-term memory involving strings/series of digits of varying length); 2) Tower of London (planning and problem solving); 3) STROOP test (Stroop Color and Word Test); 4) Symbol Digit Modalities Test (processing speed of visual stimuli); 5) Rey-Osterrieth Complex Figure Test (ROCF) (visuomotor integration).

Inclusion Criteria:

1. sub-acute patients, with ischemic or hemorrhagic stroke, documented by MRI or CT;
2. age between 55 and 85 years;
3. patients able to perform a rehabilitation treatment focused on the UL, for at least 45 min/day, for 5 days/week;
4. time latency since stroke ranging from 2 weeks to 6 months,
5. cognitive and language abilities sufficient to understand the experiments and follow instructions.

Exclusion Criteria:

1. a previous stroke;
2. behavioral and cognitive disorders and/or reduced compliance interfering with active therapy;
3. fixed contraction deformity in the affected limb interfering with active therapy (ankylosis, Modified Ashworth Scale = 4);
4. severe deficits in visual acuity;
5. upper extremity Fugl-Meyer score >58.

The investigators will enroll both inpatients and outpatients admitted to their rehabilitation facility with an upper limb impairment due to neurologic or orthopedic disorders.