Inclusion Criteria:  Signed and dated informed consent prior to any study-related procedures (Caregivers); Patients whose parents/legal representatives have been thoroughly informed of the aim of the study procedures and provided signed and dated written informed consent; Male patients between 5 and 17 years old (less than 18 years old); Need for urethroplasty in failed hypospadias treatment; Hypospadias complications shown by clinical evaluation, uroflowmetry with post-micturition residual evaluation and/or retrograde urethrography and/or urethroscopy; Uroflowmetry rate: Uroflowmetry with a plateau-shaped curve and low qmax according to paediatric uroflow normograms; Absence of other contraindications to HOLOUR implantation based on investigator's judgement; A cooperative attitude to follow up the study procedures (Caregivers in case of minors).  Exclusion Criteria:  Known or suspected intolerances against anaesthesia; Bad general condition (ECOG index >2); Clinical and/or laboratory signs of acute systemic infections and/or severe inflammation at the time of screening. Patient can be re-screened after appropriate treatment; Severe systemic disease (i.e. uncompensated diabetes); Stenosis or retraction secondary to medical conditions other than hypospadias failure (i.e. radiotherapy, lichen sclerosis, etc…);  Allergy, sensitivity or intolerance to drugs or excipients (hypersensitivity to any of the excipients listed in Investigator's brochure or in this protocol):  Transport medium (Dulbecco's Modified Eagles Medium supplemented with L-glutamine) Fibrin support; Contraindications to the post- treatment local or systemic antibiotics and/or corticosteroids; UTI or urine culture positive requiring a re-screening of patient; Contraindications to undergo extensive surgical procedures; Clinically significant or unstable concurrent disease or other clinical contraindications to stem cell implantation based on investigator's judegment or other concomitant medical conditions affecting grafting procedure; Patients and parents/tutor unlikely to comply with the study protocol or unable to understand the nature and scope of the study or the possible benefits or unwanted effects of the study procedures and treatments; Participation in another clinical trial where conventional investigational drug was received less than 1 months prior to screening visit; Patients who received surgical procedure within 6 months prior to screening visit; Anaesthesia or severe hypoesthesia of the area; Diagnosis of local or systemic neoplastic disease.