Knockdown Indian Hedgehog (Ihh) does not delay Fibular Fracture Healing in genetic deleted Ihh mice and pharmaceutical inhibited Ihh Mice

Sci Rep. 2018 Jul 9;8(1):10351. doi: 10.1038/s41598-018-28657-7.

Abstract

The objective of this study was to determine if Ihh is required for fracture healing. Fibular fracture was created in adult Col2a1-CreERT2; Ihhfl/fl mice. Ihhfl/fl mice received Tamoxifen (TM) to delete Ihh. WT mice received Cyclopamine to inhibit Hh pathway. Callus tissue properties and Ihh pathway were analyzed at 1, 2, and 3 weeks post-fracture by X-ray, micro-CT, mechanical test, RT-PCR and immunohistochemistry. Deleted Ihh was evidenced by the occurrence of growth plate closure in the Ihhfl/fl mice by X-ray 3 weeks after TM treatment. All mice showed fracture healing at 3 weeks post-operation. Histology analysis indicated that, compared to the control, cartilage area was less in fracture sites from Ihh deficient animals by either genetic deletion or drug inhibition at 1 and 2 weeks post-fracture. Ihh immunostaining and its mRNA level were diminished in the fracture callus in Ihh reduced mice. There was no significant difference in BV/TV, BMD and mechanical test. Interruption to Ihh pathway by either genetic or pharmaceutical approach didn't affect fibular fracture healing in these mice. This surprised finding implicates that the deleted Ihh does not affect fracture healing in this model.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chondrocytes / cytology
  • Chondrocytes / metabolism
  • Collagen Type II / metabolism
  • Disease Models, Animal
  • Down-Regulation / drug effects
  • Fibula / pathology
  • Fracture Healing / physiology*
  • Fractures, Bone / diagnostic imaging
  • Fractures, Bone / pathology*
  • Hedgehog Proteins / antagonists & inhibitors
  • Hedgehog Proteins / genetics
  • Hedgehog Proteins / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Signal Transduction / drug effects
  • Veratrum Alkaloids / pharmacology
  • X-Ray Microtomography
  • Zinc Finger Protein GLI1 / metabolism

Substances

  • Collagen Type II
  • Gli1 protein, mouse
  • Hedgehog Proteins
  • Veratrum Alkaloids
  • Zinc Finger Protein GLI1
  • ihh protein, mouse
  • cyclopamine