This pilot interventional study evaluates the safety and preliminary efficacy of treatment with allogeneic mesenchymal stromal stem cells (MSCs) derived from umbilical cord tissue in patients with radiation-induced xerostomia after radiotherapy for head and neck cancer. Xerostomia is a frequent late adverse effect of radiotherapy and can significantly impair oral function and quality of life.

Participants receive a single administration of allogeneic MSCs as the study intervention and are followed for clinical outcomes. The study evaluates safety, salivary gland function, subjective xerostomia symptoms, and imaging-based changes in salivary gland tissue.

The results of this pilot study may support the development of regenerative treatment strategies for radiation-induced salivary gland damage.

This is a prospective pilot interventional clinical study designed to assess the safety and preliminary efficacy of treatment of radiation-induced xerostomia using allogeneic mesenchymal stromal stem cells (MSCs) derived from umbilical cord tissue. Radiation-induced xerostomia is a common late complication in patients treated with radiotherapy for head and neck cancer and is associated with reduced salivary flow, impaired oral health, swallowing difficulties, and decreased quality of life.

Allogeneic MSCs are characterized by strong immunomodulatory properties and regenerative potential. In this study, MSCs obtained from umbilical cord tissue are administered as a therapeutic intervention to evaluate their potential to improve salivary gland function and reduce symptoms of xerostomia.

The primary objective of the study is to assess the safety of MSC administration, with follow-up monitoring for adverse events during a four-month period after the intervention.

Secondary objectives include evaluation of preliminary efficacy of MSC therapy by assessing:

subjective xerostomia symptoms and patient-reported outcomes,

salivary flow and salivary quality parameters,

radiological, scintigraphic, and morphological changes of salivary gland tissue following treatment.

Participants undergo structured clinical evaluations and follow-up assessments according to the study protocol. The study aims to provide early evidence on feasibility and potential clinical benefit of MSC-based therapy for the treatment of radiation-induced xerostomia.

Inclusion Criteria:

• Adults aged 18 years or older
• History of radiotherapy for head and neck cancer
• Presence of radiation-induced xerostomia
• Completed oncological treatment
• Ability to understand the study procedures and provide written informed consent

Exclusion Criteria:

• Active malignant disease requiring ongoing oncological treatment
• Acute infection or inflammation in the oral cavity or salivary glands
• Severe systemic disease or condition that could influence study results
• Contraindication to the planned intervention (MSC administration)
• Pregnancy or breastfeeding
• Any condition that, in the investigator's opinion, would interfere with participation or evaluation of outcomes