Administration of Human Non-Diabetic Mesenchymal Stromal Cells to a Murine Model of Diabetic Fracture Repair: A Pilot Study.

Luke Watson,Laoise M Mcnamara,Aoife Carbin,Patrick Mcdonnell,Xi Zhe Chen,Cynthia M Coleman,Lisa O’Flynn,David Connolly,Paul G Loftus,Aideen E Ryan,Timothy O’Brien,Áine Fleming,Emma Horan

doi:10.3390/cells9061394

Abstract

Individuals living with type 1 diabetes mellitus may experience an increased risk of long bone fracture. These fractures are often slow to heal, resulting in delayed reunion or non-union. It is reasonable to theorize that the underlying cause of these diabetes-associated osteopathies is faulty repair dynamics as a result of compromised bone marrow progenitor cell function. Here it was hypothesized that the administration of non-diabetic, human adult bone marrow-derived mesenchymal stromal cells (MSCs) would enhance diabetic fracture healing. Human MSCs were locally introduced to femur fractures in streptozotocin-induced diabetic mice, and the quality of de novo bone was assessed eight weeks later. Biodistribution analysis demonstrated that the cells remained in situ for three days following administration. Bone bridging was evident in all animals. However, a large reparative callus was retained, indicating non-union. µCT analysis elucidated comparable callus dimensions, bone mineral density, bone volume/total volume, and volume of mature bone in all groups that received cells as compared to the saline-treated controls. Four-point bending evaluation of flexural strength, flexural modulus, and total energy to re-fracture did not indicate a statistically significant change as a result of cellular administration. An ex vivo lymphocytic proliferation recall assay indicated that the xenogeneic administration of human cells did not result in an immune response by the murine recipient. Due to this dataset, the administration of non-diabetic bone marrow-derived MSCs did not support fracture healing in this pilot study.

Highlights

Type 1 diabetes mellitus (T1DM) is an autoimmune disorder in which the immune system destroys insulin-producing beta cells, leading to elevated blood glucose levels
Adult human bone marrow-derived mesenchymal stromal cells (MSCs) were cultured in α-minimal essential medium (α-MEM), with 10% fetal bovine serum (FBS), 100 U/mL penicillin, 100 μg/mL streptomycin, 1% non-essential amino acids (NEAA), and 1 ng/mL fibroblast growth factor (FGF-2) in an incubator at 37 ◦ C with 2% O2 and 5% CO2 at 90% humidity
As the presence of T1DM results in reduced osteogenic potential in rodent progenitor cells [22,23] and in vitro models of high-glucose exposure indicate similar results with human MSCs [24], it was hypothesized that deficiencies in host progenitor cell capacity results in inhibited fracture repair

Summary

Introduction

Type 1 diabetes mellitus (T1DM) is an autoimmune disorder in which the immune system destroys insulin-producing beta cells, leading to elevated blood glucose levels. Patients with T1DM can develop early onset osteopenia or osteoporosis [1,2] and, as a consequence, have an increased risk of fracture [3,4]. Long bone fractures in diabetic patients take up to 163% longer to heal than non-diabetic fractures [5], resulting in an increased risk of complications including delayed reunion, non-union, or pseudoarthrosis. The diabetic fracture callus contains reduced expression of chondrogenic markers and a decreased callus cross sectional area [10], indicative of reduced immunoregulatory and differentiation potential of reparative bone marrow progenitor cells. Compounding this imbalance, fractured streptozotocin (STZ)-treated mice have a 78%

Methods

Results

Discussion

Conclusion