Dietary vitamin D supplementation can potentially offer a benefit to those with adolescent idiopathic scoliosis (AIS), according to new research which found that a significantly higher occurrence and severity of scoliosis induced by a vitamin D deficient diet suggested that vitamin D deficiency may play a role in the initiation of AIS.
The preclinical animal study, which won Best Basic Science Paper at the Scoliosis Research Society’s 29th International Meeting on Advanced Spine Techniques (IMAST 2022; 6–9 April; Miami, USA), was presented by Jian Cao (Rutgers Cancer Institute of New Jersey, New Brunswick, USA).
Speaking to Spinal News International, Cao said: “Current clinical evidence suggested an important role of vitamin D deficiency in AIS patients, but the missing gap now is the connection between bone turnover, vitamin D deficiency and scoliosis development.
“Our findings are the initial proof of clinical concept by a valid animal model, and provide insight for the further clinical translation. We are also trying to solve these potential questions, including the dosages and indications of vitamin D application, and start clinical validation in multicentre studies. We believe that the therapy will benefit the carefully selected AIS patient in the near future.”
The research team, which was led by Zhen Liu (The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China), hypothesised that dietary vitamin D supplementation would improve the bone parameters and reduce scoliotic curvature in a bipedal mice model.
A total of 90 C57B6/j male mice were divided into six groups: vitamin D deficiency (0 IU/kg, G1), normal vitamin D (1,000 IU/kg, G2), 2,000 IU/kg (G3), 3,000 IU/kg (G4 group) 8,000 IU/kg (G5) and 9,000 IU/kg (G6).
The bipedal mice model was established at four weeks old. X-ray and Micro-CT was performed to monitor the occurrence of scoliosis and bone microarchitecture. The serum levels of vitamin D, terminal peptide collagen type I (CTX-1), and Osteocalcin were quantified by enzyme-linked immunosorbent assay (ELISA) test. Tartrate-resistant acid phosphatase staining of osteoclasts (TRAP) staining of the L5 vertebra was performed to assess the osteoclast activity.
In G1, the incidence and severity of scoliosis were significantly higher from week eight to week 16 compared to the other five groups.
Compared to the Cobb angle in G2 with normal diet (16.7° ± 3.7°), the severity of scoliosis was significantly reduced in G5 and G6 at week 16. The trabecular bone microarchitecture was found to be enhanced in the G5 and G6 groups, indicated by a significant increase in bone mineral density, bone volume fraction, and trabecular thickness.
Serum 25(OH)D3 levels were significantly reduced in G1 (19.2 ng/ml) compared to that in G2 with a normal diet (42.1 ng/ml). A high dosage of vitamin D (G5 and G6) was found to rescue the vitamin D deficiency and the increased CTX-1 and Osteocalcin in the G1 group. TRAP staining showed an increased osteoclast number in G1, which was attenuated by vitamin D supplementation in G4, G5, and G6.