Human iPSC-derived iMSCs improve bone regeneration in mini-pigs

Pascal Jungbluth,Stephan Tanner,Martina Bohndorf,Wasco Wruck,Johannes Schneppendahl,James Adjaye,Mohssen Hakimi,Md Shaifur Rahman,Joachim Windolf,David Latz,Patric Kröpil,Martin Sager,Vera Grotheer,Jan Grassmann,Lucas-Sebastian Spitzhorn

doi:10.1038/s41413-019-0069-4

Abstract

Autologous bone marrow concentrate (BMC) and mesenchymal stem cells (MSCs) have beneficial effects on the healing of bone defects. To address the shortcomings associated with the use of primary MSCs, induced pluripotent stem cell (iPSC)-derived MSCs (iMSCs) have been proposed as an alternative. The aim of this study was to investigate the bone regeneration potential of human iMSCs combined with calcium phosphate granules (CPG) in critical-size defects in the proximal tibias of mini-pigs in the early phase of bone healing compared to that of a previously reported autograft treatment and treatment with a composite made of either a combination of autologous BMC and CPG or CPG alone. iMSCs were derived from iPSCs originating from human fetal foreskin fibroblasts (HFFs). They were able to differentiate into osteoblasts in vitro, express a plethora of bone morphogenic proteins (BMPs) and secrete paracrine signaling-associated cytokines such as PDGF-AA and osteopontin. Radiologically and histomorphometrically, HFF-iMSC + CPG transplantation resulted in significantly better osseous consolidation than the transplantation of CPG alone and produced no significantly different outcomes compared to the transplantation of autologous BMC + CPG after 6 weeks. The results of this translational study imply that iMSCs represent a valuable future treatment option for load-bearing bone defects in humans.

Highlights

The majority of bone fractures heal without complications.cases involving bone nonunion and large skeletal bone defects represent a challenge for orthopedic surgery
The aim of this study was to evaluate the feasibility and impact of the use of a composite made of human iMSCs and calcium phosphate granules (CPG) for bone regeneration compared with that of a previously investigated autograft treatment, a composite made of autologous bone marrow concentrate (BMC) and CPG, and CPG alone in a critical-size long bone defect in mini-pigs under weightbearing conditions in the early phase of bone healing
Characterization of the human fetal foreskin fibroblasts (HFFs)-iMSCs The HFF-induced pluripotent stem cell (iPSC) were differentiated into HFF-iMSCs using a 14-day protocol that utilized the inhibition of the TGFβ pathway by SB431542.17 HFF-iMSCs showed a typical fibroblast spindleshaped morphology and expressed the mesenchymal stem cells (MSCs) markers PDGFRβ and Vimentin

Summary

Introduction

The majority of bone fractures heal without complications. Cases involving bone nonunion and large skeletal bone defects represent a challenge for orthopedic surgery. Despite its significant drawbacks, including donor site morbidity, limited availability, and poor bone quality, autologous bone grafting remains the gold standard for treatment.[1] The use of autologous bone marrow concentrate (BMC) or mesenchymal stem cells (MSCs) have been described as alternative treatment options for improving bone regeneration.[2,3]. BMC contains stem cells, growth factors, and immune cells and have been shown to improve bone regeneration.[4] MSCs are multipotent, which is manifested in their ability to differentiate into adipocytes, chondrocytes and osteoblasts in vitro.[5,6,7,8]

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