Shire PLC, an Irish company that has more than 1,650 employees at its Human Genetic Therapies campus in Lexington, said it has agreed to acquire Lotus Tissue Repair Inc., a small Cambridge company, for an undisclosed amount.

Shire’s HGT unit in Lexington develops therapies to treat rare diseases. Lotus Tissue Repair, for its part, is is developing a protein replacement therapy as a potential treatment for dystrophic epidermolysis bullosa, or DEB, a devastating rare disease.