Osseointegration of acellular and cellularized osteoconductive scaffolds: Is tissue engineering using mesenchymal stem cells necessary for implant fixation?

Abstract

The main issue associated with revision total hip replacements (rTHRs) is how to generate new bone adjacent to implants and achieve fixation of the revision implant. In its simplest form, bone tissue engineering (BTE) combines cells and scaffolds in vitro to replace damaged or lost bone in vivo. Our aim was to develop BTE porous TiAl6V4 constructs with a calcium-phosphate coating without or with mesenchymal stem cells (MSCs) seeded throughout the entire porous structure to enhance new bone formation and which could be used for rTHRs. Porous titanium scaffolds made by selective laser sintering were seeded throughout with autologous bone marrow MSCs and cultured in a perfusion bioreactor. Constructs were implanted in the medial femoral condyle of 20 skeletally mature mule sheep with and without a gap of 2.5 mm between the construct and the host bone. After 6 weeks, the addition of MSCs to the scaffolds did not significantly increase osseointegration or implant-bone fixation strength. However, in the defects with a gap, the cellularized constructs showed higher implant-bone contact area and implant-bone fixation strength. BTE can be applied to develop acellular or cellularized constructs with clinical application in rTHRs where a lack of bone stock is problematic.

Effects of bone substitute architecture and surface properties on cell response, angiogenesis, and structure of new bone

“…The manufacturing technique in turn determines the accuracy and control over the architecture of the bone substitute. For metal bone substitutes, selective laser melting (SLM), 10-16 selective laser sintering (SLS), 17 sintering, 18 perforating titanium sheet 14 and capsule-free hot isostatic pressing (CF-HIP) 19 were used. Those manufacturing techniques differ in terms of their production accuracy.…”

“…9 Depending on the biomaterial used (polymer, ceramic, or metal) (Table 1), different fabrication techniques could be applied to manufacture the designed porous biomaterials. For metal bone substitutes, selective laser melting (SLM), [10][11][12][13][14][15][16] selective laser sintering (SLS), 17 sintering, 18 perforating titanium sheet 14 and capsule-free hot isostatic pressing (CF-HIP) 19 are some examples of the applicable production methods. Polymer and ceramic bone substitutes could be manufactured with porogen leaching, [20][21][22][23][24][25][26][27][28][29][30] freeze drying, 31 3D printing of successive fibre/strut layers, [32][33][34][35][36] electrospinning, 37 or gas foaming.…”

“…Surface characteristics are important for adhesion, attachment, and spreading of cells on the surface of biomaterials. 89 In addition to the biomaterial a bone substitute is made of, the use of surface treatments,16 addition of a silk 74 or CaP coating, 17 and integration of HA particles, 25,28,29,37 or HA wiskers, 30 may affect the surface roughness and can improve the bioactivity of a porous biomaterial. 58 Incorporation of CaP coatings, such as HA particles or whiskers, are thought to improve bone formation in porous biomaterials.…”

Biofilm formation in total hip arthroplasty: prevention and treatment

“…In addition to the impaired HID, certain biomaterials and/or superficial coatings can physically, chemically and biologically support and enhance microbial growth [40][41][42][43][44] . Coatings and biomaterial surfaces often incorporate superficial pores in order to encourage ingrowth of host tissue into the implant thus mediating successful integration 45,46 . Unfortunately, these pores constitute superficial niches that physically protect microbes from phagocytic cells.…”

Biological Strategies for Improved Osseointegration and Osteoinduction of Porous Metal Orthopedic Implants

“…increased new bone formation and improved the recovery of bone gap defects in mule sheep(100). In humans, mesenchymal stem/stromal cells (MSCs) have promising potential in orthopedic surgery and ancillary treatments(101).…”