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Item type:Publication, Access status: without files , Reduced bone regeneration in rats with type 2 Diabetes Mellitus as a result of impaired stromal cell and osteoblast function : a computer modeling study(Wiley, 2023-11-01); ; ; Bone has the fascinating ability to self-regenerate. However, under certain conditions, such as type 2 diabetes mellitus (T2DM), this ability is impaired. T2DM is a chronic metabolic disease known by the presence of elevated blood glucose levels that is associated with reduced bone regeneration capability, high fracture risk, and eventual non-union risk after a fracture. Several mechanical and biological factors relevant to bone regeneration have been shown to be affected in a diabetic environment. However, whether impaired bone regeneration in T2DM can be explained due to mechanical or biological alterations remains unknown. To elucidate the relevance of either one, the aim of this study was to investigate the relative contribution of T2DM-related alterations on either cellular activity or mechanical stimuli driving bone regeneration. A previously validated in silico computer modeling approach that was capable of explaining bone regeneration in uneventful conditions of healing was further developed to investigate bone regeneration in T2DM. Aspects analyzed included the presence of mesenchymal stromal cells (MSCs), cellular migration, proliferation, differentiation, apoptosis, and cellular mechanosensitivity. To further verify the computer model findings against in vivo data, an experimental setup was replicated, in which regeneration was compared in healthy and diabetic after a rat femur bone osteotomy stabilized with plate fixation. We found that mechanical alterations had little effect on the reduced bone regeneration in T2DM and that alterations in MSC proliferation, MSC migration, and osteoblast differentiation had the highest effect. In silico predictions of regenerated bone in T2DM matched qualitatively and quantitatively those from ex vivo μCT at 12 weeks post-surgery when reduced cellular activities reported in previous in vitro and in vivo studies were included in the model. The presented findings here could have clinical implications in the treatment of bone fractures in patients with T2DM. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.Publicationtype: Journal Article11 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Effects of insulin therapy on porosity, non-enzymatic glycation and mechanical competence in the bone of rats with type 2 diabetes mellitusType 2 diabetes mellitus increases skeletal fragility; however, the contributing mechanisms and optimal treatment strategies remain unclear. We studied the effects of diabetes and insulin therapy on non-enzymatic glycation (NEG), cortical porosity (Ct.Po) and biomechanics of the bone tissue in Zucker Diabetic Fatty (ZDF) rats. Eleven-week old ZDF diabetic and non-diabetic rats were given insulin to achieve glycaemic control or vehicle seven days per week over twelve weeks (insulin dose adapted individually 0.5 international units (IU) at week 1 to 13.0 IU at week 12). The right femora were excised, micro-CT scanned, and tested in 3-point bending to measure biomechanics. NEG of the midshaft was determined from bulk fluorescence. Diabetes led to increased NEG (+ 50.1%, p = 0.001) and Ct.Po (+ 22.9%, p = 0.004), as well as to reduced mechanical competence (max. stress: − 14.2%, p = 0.041, toughness: − 29.7%, p = 0.016) in the bone tissue. NEG and Ct.Po both correlated positively to serum glucose (NEG: R2 = 0.41, p < 0.001, Ct.Po: R2 = 0.34, p = 0.003) and HbA1c (NEG: R2 = 0.42, p < 0.001, Ct.Po: R2 = 0.28, p = 0.008) levels, while NEG correlated negatively with bone biomechanics (elastic modulus: R2 = 0.21, p = 0.023, yield stress: R2 = 0.17, p = 0.047). Twelve weeks of insulin therapy had no significant effect on NEG or Ct.Po, and was unable to improve the mechanical competence of the bone tissue. A reduction of mechanical competence was observed in the bone tissue of the diabetic rats, which was explained in part by increased collagen NEG. Twelve weeks of insulin therapy did not alter NEG, Ct.Po or bone biomechanics. However, significant correlations between NEG and serum glucose and HbA1c were observed, both of which were reduced with insulin therapy. This suggests that a longer duration of insulin therapy may be required to reduce the NEG of the bone collagen and restore the mechanical competence of diabetic bone.Publicationtype: Journal Article133 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Effects of parathyroid hormone on cortical porosity, non-enzymatic glycation and bone tissue mechanics in rats with type 2 diabetes mellitusType 2 diabetes mellitus increases skeletal fragility; however, the contributing mechanisms and the efficacy of bone-forming agents are unclear. We studied diabetes and parathyroid hormone (PTH) treatment effects on cortical porosity (Ct.Po), non-enzymatic glycation (NEG) and bone mechanics in Zucker diabetic fatty (ZDF) rats.Eleven-week old ZDF diabetic (DB) and non-diabetic (ND) rats were given 75. μg/kg PTH (1-84) or vehicle 5. days per week over 12. weeks. The right femora and L4 vertebrae were excised, micro-CT scanned, and tested in 3-point bending and uniaxial compression, respectively. NEG of the samples was determined using fluorescence.Diabetes increased Ct.Po (vertebra (vert): + 40.6%, femur (fem): + 15.5% vs. ND group, p < 0.05) but had no effect on NEG. PTH therapy reduced vertebral NEG in the ND animals only (- 73% vs untreated group, p < 0.05), and increased femoral NEG in the DB vs. ND groups (+ 63%, p < 0.05). PTH therapy had no effect on Ct.Po. Diabetes negatively affected bone tissue mechanics where reductions in vertebral maximum strain (- 22%) and toughness (- 42%) were observed in the DB vs. ND group (p < 0.05). PTH improved maximum strain in the vertebra of the ND animals (+ 21%, p < 0.05) but did not have an effect in the DB group. PTH increased femoral maximum strain (+ 21%) and toughness (+ 28%) in ND and decreased femoral maximum stress (- 13%) and toughness (- 27%) in the DB animals (treated vs. untreated, p < 0.05). Ct.Po correlated negatively with maximum stress (fem: R = - 0.35, p < 0.05, vert: R = - 0.57, p. < 0.01), maximum strain (fem: R = - 0.35, p. <. 0.05, vert: R. = - 0.43, p. < 0.05) and toughness (fem: R = - 0.34, p < 0.05, vert: R = - 0.55, p < 0.01), and NEG correlated negatively with toughness at the femur (R = - 0.34, p < 0.05) and maximum strain at the vertebra (R = - 0.49, p < 0.05).Diabetes increased cortical porosity and reduced bone mechanics, which were not improved with PTH treatment. PTH therapy alone may worsen diabetic bone mechanics through formation of new bone with high AGEs cross-linking. Optimal treatment regimens must address both improvements of bone mass and glycemic control in order to successfully reduce diabetic bone fragility.This article is part of a Special Issue entitled "Bone and diabetes".Publicationtype: Journal Article155