Impact of High-Altitude Hypoxia on Early Osseointegration With Bioactive Titanium.

Yarong Wang,Mingdeng Rong,Renlei Yuan,Zekun Gan,Peng Shang,Ziyi Liu,Wuwei Yin,Yingxin Ye,Hongxing Chu,Jian Zhang,Pei Chen,Haibin Lu

doi:10.3389/fphys.2021.689807

Yarong Wang, Mingdeng Rong + Show 10 more

Open Access

https://doi.org/10.3389/fphys.2021.689807

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Abstract

Nowadays, the bone osseointegration in different environments is comparable, but the mechanism is unclear. This study aimed to investigate the osseointegration of different bioactive titanium surfaces under normoxic or high-altitude hypoxic environments. Titanium implants were subjected to one of two surface treatments: (1) sanding, blasting, and acid etching to obtain a rough surface, or (2) extensive polishing to obtain a smooth surface. Changes in the morphology, proliferation, and protein expression of osteoblasts on the rough and smooth surfaces were examined, and bone formation was studied through western blotting and animal-based experiments. Our findings found that a hypoxic environment and rough titanium implant surface promoted the osteogenic differentiation of osteoblasts and activated the JAK1/STAT1/HIF-1α pathway in vitro. The animal study revealed that following implant insertion in tibia of rabbit, bone repair at high altitudes was slower than that at low altitudes (i.e., in plains) after 2weeks; however, bone formation did not differ significantly after 4weeks. The results of our study showed that: (1) The altitude hypoxia environment would affect the early osseointegration of titanium implants while titanium implants with rough surfaces can mitigate the effects of this hypoxic environment on osseointegration, (2) the mechanism may be related to the activation of JAK1/STAT1/HIF-1α pathway, and (3) our results suggest the osteogenesis of titanium implants, such as oral implants, is closely related to the oxygen environment. Clinical doctors, especially dentists, should pay attention to the influence of hypoxia on early osseointegration in patients with high altitude. For example, it is better to choose an implant system with rough implant surface in the oral cavity of patients with tooth loss at high altitude.

Highlights

The theory of “osseointegration” has existed for more than 50 years (Lee and Bance, 2019)
The plate was incubated for 3 h, and cell adherence to titanium was confirmed by scanning electron microscopy (SEM)
Scanning electron microscopy analysis showed that mechanical polishing resulted in a smooth, “mirror-like” titanium surface (Figure 1A), whereas the sandblasted and acid-etched surface was rough and displayed a “honeycomb” structure with different porosities (Figure 1D)

Summary

Introduction

The theory of “osseointegration” has existed for more than 50 years (Lee and Bance, 2019). The hypoxic atmosphere characteristic of high-altitude environments in plateau regions is associated with a higher risk of osteoporosis and a longer healing time of bone fractures in the elderly population compared to those from regions of low altitudes, such as plains (Bernardi et al, 2020; Feng et al, 2020). This suggests that oxygen concentration is an important factor for bone defect repair. The osteogenesis of implants in different environment was evaluated in Xizang, China (highland zone, altitude near 3,000 m, severe cold; Liu et al, 2021) and Guangzhou, China (plain zone, altitude near 1,000 m, Warm and rainy; Liu et al, 2020a)

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