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Osteogenic cell sheets reinforced with photofunctionalized micro-thin titanium

Significance statement

The technology advancement described in the paper is based on the recent discovery of photofunctionalization. Photofunctionalization is a rapid conditioning of dental implants and titanium-based materials with UV (ultraviolet) light immediately prior to use. The images at below are the examples representing how the surface property of dental implants can be enhanced by photofunctionalization. The hydrophobic surfaces are transformed to super-hydrophilic surfaces. Photofunctionalization increases recruitment, attachment, spreading, and proliferation of osteogenic cells on titanium surfaces, resulting in the increased bone formation and stronger anchorage of implants. Recent studies also revealed that photofunctionalized titanium attracts a remarkably less number of bacteria compared to identical as-received titanium, providing a novel way to mitigate or potentially prevent infection and inflammatory reactions around implants. As an exemplary benefit of photofunctionalization in tissue engineering, this paper describes successful construction of osteogenic cell sheets supported by micro-thin titanium. More information is available for photofunctionalization at http://www.photofunc-implant.org/

Figure legend: Dental implants are transformed from hydrophobic to super-hydrophilic state after a 12 min treatment with UV light of optimized wavelength and strength. This surface conditioning is defined as photofunctionalization. In addition to the advent of super-hydrophilic surfaces, photofunctionalization removes hydrocarbon from titanium surfaces, resulting in a remarkable increase in their osteoconductivity. The photofunctionalization is proven effective in any surface types of any titanium-based materials tested.

Osteogenic cell sheets reinforced with photofunctionalized micro-thin titanium. Global Medical Discovery

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Journal Reference

Ishijima M1, Hirota M2, Park W2, Honda MJ3, Tsukimura N1, Isokawa K3, Ishigami T4, Ogawa T5. J Biomater Appl. 2015  pii: 0885328214567693.

Show Affiliations

1Laboratory of Bone and Implant Sciences (LBIS), The Weintraub Center for Reconstructive Biotechnology, Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, UCLA School of Dentistry, Los Angeles, CA, USA Department of Partial Denture Prosthodontics, Nihon University School of Dentistry, Tokyo, Japan.

2Laboratory of Bone and Implant Sciences (LBIS), The Weintraub Center for Reconstructive Biotechnology, Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, UCLA School of Dentistry, Los Angeles, CA, USA.

3Department of Anatomy, Nihon University School of Dentistry, Tokyo, Japan.

4Department of Partial Denture Prosthodontics, Nihon University School of Dentistry, Tokyo, Japan.

5Laboratory of Bone and Implant Sciences (LBIS), The Weintraub Center for Reconstructive Biotechnology, Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, UCLA School of Dentistry, Los Angeles, CA, USA [email protected]

 

Abstract

Cell sheet technology has been used to deliver cells in single-sheet form with an intact extracellular matrix for soft tissue repair and regeneration. Here, we hypothesized that titanium-reinforced cell sheets could be constructed for bone tissue engineering and regeneration. Fifty-µm-thick titanium plates containing apertures were prepared and roughened by acid etching, some of which were photo functionalized with 12 min of UV light treatment. Cell sheets were prepared by culturing rat calvarial periosteum-derived cells on temperature-responsive culture dishes and attached to titanium plates. Titanium-reinforced osteogenic cell sheet construction was conditional on various technical and material factors: cell sheets needed to be double-sided and sandwich the titanium plate, and the titanium plates needed to be micro thin and contain apertures to allow close apposition of the two cell sheets. Critically, titanium plates needed to be UV-photofunctionalized to ensure adherence and retention of cell sheets. Single-sided cell sheets or double-sided cell sheets on as-made  titanium  contracted and deformed within 4 days of incubation. Titanium-reinforced cell sheets on photo-functionalized titanium were structurally stable at least up to 14 days, developed the expected osteogenic  phenotypes (ALP production and mineralization), and maintained structural integrity without functional degradation. Successful construction of titanium-reinforced osteogenic cell sheets was associated with increased cell attachment, retention, and expression of vinculin, an adhesion protein by photo-functionalization. This study identified the technical and material requirements for constructing  titanium-reinforced osteogenic cell sheets. Future in vivo studies are warranted to test these titanium-reinforced cell sheets as stably transplantable, mechanically durable, and shape controllable  osteogenic devices.

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