Osteopontin, osteocalcin, and osteoprotegerin expression in human tissue affected by cleft lip and palate

Institute of Anatomy and Anthropology, Department of Morphology, Rīga Stradiņš University, Riga, Latvia

Abstract

Cleft lip and palate (CLP) is a common congenital anomaly with a complex etiology which has not been elucidated yet. This study investigated whether expression of osteopontin (OPN), osteoprotegerin (OPG), and osteocalcin (OC), which are essential for the normal craniofacial bone remodelling, is not regulated in children with CLP. Alveolar bone tissue samples were obtained from patients with complete bilateral (CB) CLP (n = 14) during corrective plastic surgery and unaffected control subjects (n = 9). OPN, OPG, and OC expression was assessed by immunohistochemistry, and data were analyzed with the Mann-Whitney test. OPN expression was observed only sporadically in the alveolar bone of 3 patients, in contrast to the control group (z = −2.962; P < 0.003). The number of OPG-positive bone cells varied from occasional to moderate, in contrast to the control group (z = −2.247; P = 0.025). OC-positive osteocytes were present in moderate to numerous numbers in both patients and controls, with no significant difference between them (z = −1.356; P < 0.175). The prominent expression of OC characteristic for CBCLP affected hard tissue indicates a high potential of bone mineralization. Few OPG-positive osteocytes in the bone tissue implicate the disregulation of osteoclast differentiation, maturation, and activity, but few OPN-containing cells may prove the common disregulation of bone remodelling during cleft morphopathogenesis.