eCM (Eur Cell Mater / e Cells & Materials) Not-for-Profit Open Access
Created by Scientists, for Scientists
 ISSN:1473-2262         NLM:100973416 (link)         DOI:10.22203/eCM

2021   Volume No 41 – pages 345-354

Title: Healing of sub-critical femoral osteotomies in mice is unaffected by tacrolimus and deletion of recombination activating gene 1

Authors: T-Y Liu, M Bartnikowski, AC Wu, M Veitch, KA Sokolowski, SM Millard, AR Pettit, V Glatt, CH Evans, JW Wells

Address: The University of Queensland Diamantina Institute, 37 Kent Street, Woolloongabba, QLD 4102, Australia

E-mail: j.wells3 at

Abstract: Clinical management of delayed healing or non-union of long bone fractures and segmental defects poses a substantial orthopaedic challenge. There are suggestions in the literature that bone healing may be enhanced by inhibiting the activities of T and B lymphocytes, but this remains controversial. To examine this matter in more detail, sub-critical-sized segmental defects were created in the femora of mice and it was assessed whether there might be a benefit from the administration of a Food and Drug Administration (FDA)-approved drug that blocks T cell activation (tacrolimus). Defects were stabilised using an internal plate. In certain groups of animals, 1 mg/kg or 10 mg/kg tacrolimus was delivered locally to the defect site for 3 or 7 d using an implanted osmotic pump with a silicon catheter directing drug delivery into the defect area. Healing was monitored by weekly X-ray and assessed at 12 weeks by mechanical testing, µCT and histology. Radiographic and histological evaluations revealed that 100 % of defects healed well regardless of tacrolimus dosage or duration. A comparison of healed C57BL/6 and Rag1−/− femora by µCT and ex vivo torsion testing showed no differences within mouse strains in terms of bone volume, tissue volume, bone volume/tissue volume ratio, shear modulus, torsional rigidity or torsional stiffness. These data failed to support an important role for tacrolimus in modulating the natural healing of segmental defects under those experimental conditions.

Key Words: Tacrolimus, FK506, bone healing, immunosuppression, local administration, mouse.

Publication date: March 17th 2021

Article download: Pages 345-354 (PDF file)

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