Comprehensive geriatric assessment predicts azacitidine treatment duration and survival in older patients with myelodysplastic syndromes.

BACKGROUND: Treatment of older patients with myelodysplastic syndrome (MDS) is based on disease biology and performance status. Performance status, however, does not reflect increasing co-morbidities, functional dependence or psychosocial issues in older patients. PATIENTS AND METHODS: This prospective study evaluated the burden of geriatric related health issues, assessed feasibility of "tailored" Comprehensive Geriatric Assessment (CGA), and compared treatment duration and survival in older patients with MDS and oligoblastic acute myeloid leukemia with and without deficits in CGA domains (n = 98). RESULTS: Although only 27 (28%) patients had an Eastern Cooperative Oncology Group score ≥2, 78% (n = 77) patients had deficits in at least one CGA domain. Deficits were spread across all CGA domains, including dependence for instrumental activity of daily living (iADL; n = 33, 34%). Importantly, patients who were dependent for iADL (3.7 ±â€¯2.6 vs 12.1 ±â€¯7.9; p = .009), had cognitive impairment (3.5 ±â€¯2.1 vs. 10.9 ±â€¯7.9; p = .034) or impaired mobility (3.8 ±â€¯2.5 vs. 13.2 ±â€¯7.6; p = .001) completed significantly less azacitidine cycles as compared to those without these deficits. Cox-proportional regression showed that iADL dependency (hazard ratio 3.37; p = .008) and higher comorbidities (hazard ratio 4.7; p < .001) were associated with poor prognosis independent of disease related factors. Poor survival of iADL dependent patients was seen in both azacitidine (6 vs 19 months; p < .001) and supportive care cohorts (26 vs 48 months; p = .01). CONCLUSION: CGA detected geriatric related health issues, predicted poor survival and identified patients less likely to continue and benefit from azacitidine. Hence, CGA should be included in the treatment decision algorithm of older patients with MDS.

Cell Signaling in Tenocytes: Response to Load and Ligands in Health and Disease.

Signaling in tenocytes during development, homeostasis and injury involves multiple and redundant pathways. Given that tendons transmit mechanical forces from muscle to bone to effect movement, a key function for tenocytes is the detection of and response to mechanical stimulation. Mechanotransduction involves matrix-integrin-cytoskeleton to nucleus signaling, gap junction intercellular communication, changes in intracellular calcium (Ca(2+)), activation of receptors and their pathways, and responses to biochemical factors such as hormones, growth factors, adenosine triphosphate (ATP) and its derivatives, and neuromodulators. The primary cilium also plays a key role in the detection of mechanical signals. During development, transforming growth factor-ß (TGF-ß), bone morphogenetic protein (BMP), and hedgehog (Hh) signaling modulate tendon differentiation and formation. The response to injury is complex and varied involving not only inflammatory mediators such as interleukin-1ß but also mechanosensing. This chapter reviews the signaling pathways tenocytes use during mechanotransduction, development and in response to injury.

Cyclic tensile strain enhances osteogenesis and angiogenesis in mesenchymal stem cells from osteoporotic donors.

We have shown that the uniaxial cyclic tensile strain of magnitude 10% promotes and enhances osteogenesis of human mesenchymal stem cells (hMSC) and human adipose-derived stem cells (hASC) from normal, nonosteoporotic donors. In the present study, MSC from osteoporotic donors were analyzed for changes in mRNA expression in response to 10% uniaxial tensile strain to identify potential mechanisms underlying the use of this mechanical loading paradigm for prevention and treatment of osteoporosis. Human MSC isolated from three female, postmenopausal osteoporotic donors were analyzed for their responses to mechanical loading using microarray analysis of over 47,000 gene probes. Human MSC were seeded in three-dimensional collagen type I constructs to mimic the organic extracellular matrix of bone and 10% uniaxial cyclic tensile strain was applied to promote osteogenesis. Seventy-nine genes were shown to be regulated within hMSC from osteoporotic donors in response to 10% cyclic tensile strain. Upregulation of six genes were further confirmed with real-time RT-PCR: jun D proto-oncogene (JUND) and plasminogen activator, urokinase receptor (PLAUR), two genes identified as potential key molecules from network analysis; phosphoinositide-3-kinase, catalytic, delta polypeptide (PIK3CD) and wingless-type MMTV integration site family, member 5B (WNT5B), two genes with known importance in bone biology; and, PDZ and LIM domain 4 (PDLIM4) and vascular endothelial growth factor A (VEGFA), two genes that we have previously shown are significantly regulated in hASC in response to this mechanical stimulus. Function analysis indicated that 10% cyclic tensile strain induced expression of genes associated with cell movement, cell proliferation, and tissue development, including development in musculoskeletal and cardiovascular systems. Our results demonstrate that hMSC from aged, osteoporotic donors are capable of enhanced osteogenic differentiation in response to 10% cyclic tensile strain with significant increases in the expression of genes associated with enhanced cell proliferation, musculoskeletal development, and angiogenesis. Surprisingly, cyclic tensile strain of magnitude 10% not only enhanced osteogenesis in hMSC from osteoporotic donors, but also enhanced expression of angiogenic factors. Better understanding and methodologies to promote osteogenesis in hMSC from elderly, osteoporotic donors may greatly facilitate achieving long-term success in bone regeneration and functional bone tissue engineering for this ever-growing patient population.

Fracture risk assessment in long-term care: a survey of long-term care physicians.

BACKGROUND: The majority of frail elderly who live in long-term care (LTC) are not treated for osteoporosis despite their high risk for fragility fractures. Clinical Practice Guidelines for the diagnosis and management of osteoporosis provide guidance for the management of individuals 50 years and older at risk for fractures, however, they cannot benefit LTC residents if physicians perceive barriers to their application. Our objectives are to explore current practices to fracture risk assessment by LTC physicians and describe barriers to applying the recently published Osteoporosis Canada practice guidelines for fracture assessment and prevention in LTC. METHODS: A cross-sectional survey was conducted with the Ontario Long-Term Care Physicians Association using an online questionnaire. The survey included questions that addressed members' attitudes, knowledge, and behaviour with respect to fracture risk assessment in LTC. Closed-ended responses were analyzed using descriptive statistics and thematic framework analysis for open-ended responses. RESULTS: We contacted 347 LTC physicians; 25% submitted completed surveys (81% men, mean age 60 (Standard Deviation [SD] 11) years, average 32 [SD 11] years in practice). Of the surveyed physicians, 87% considered prevention of fragility fractures to be important, but a minority (34%) reported using validated fracture risk assessment tools, while 33% did not use any. Clinical risk factors recommended by the OC guidelines for assessing fracture risk considered applicable included; glucocorticoid use (99%), fall history (93%), age (92%), and fracture history (91%). Recommended clinical measurements considered applicable included: weight (84%), thyroid-stimulating hormone (78%) and creatinine (73%) measurements, height (61%), and Get-Up-and-Go test (60%). Perceived barriers to assessing fracture risk included difficulty acquiring necessary information, lack of access to tests (bone mineral density, x-rays) or obtaining medical history; resource constraints, and a sentiment that assessing fracture risk is futile in this population because of short life expectancy and polypharmacy. CONCLUSION: Perceived barriers to fracture risk assessment and osteoporosis management in LTC have not changed recently, contributing in part to the ongoing care gap in osteoporosis management. Our findings highlight the importance to adapt guidelines to be applicable to the LTC environment, and to develop partnerships with stakeholders to facilitate their use in clinical practice.

Microarray analysis of human adipose-derived stem cells in three-dimensional collagen culture: osteogenesis inhibits bone morphogenic protein and Wnt signaling pathways, and cyclic tensile strain causes upregulation of proinflammatory cytokine regulators and angiogenic factors.

Human adipose-derived stem cells (hASC) have shown great potential for bone tissue engineering. However, the molecular mechanisms underlying this potential are not yet known, in particular the separate and combined effects of three-dimensional (3D) culture and mechanical loading on hASC osteogenesis. Mechanical stimuli play a pivotal role in bone formation, remodeling, and fracture repair. To further understand hASC osteogenic differentiation and response to mechanical stimuli, gene expression profiles of proliferating or osteogenically induced hASC in 3D collagen I culture in the presence and absence of 10% uniaxial cyclic tensile strain were examined using microarray analysis. About 847 genes and 95 canonical pathways were affected during osteogenesis of hASC in 3D culture. Pathway analysis indicated the potential roles of Wnt/ß-catenin signaling, bone morphogenic protein (BMP) signaling, platelet-derived growth factor (PDGF) signaling, and insulin-like growth factor 1 (IGF-1) signaling in hASC during osteogenic differentiation. Application of 10% uniaxial cyclic tensile strain suggested synergistic effects of strain with osteogenic differentiation media on hASC osteogenesis as indicated by significantly increased calcium accretion of hASC. There was no significant further alteration in the four major pathways (Wnt/ß-catenin, BMP, PDGF, and IGF-1). However, 184 transcripts were affected by 10% cyclic tensile strain. Function and network analysis of these transcripts suggested that 10% cyclic tensile strain may play a role during hASC osteogenic differentiation by upregulating two crucial factors in bone regeneration: (1) proinflammatory cytokine regulators interleukin 1 receptor antagonist and suppressor of cytokine signaling 3; (2) known angiogenic inductors fibroblast growth factor 2, matrix metalloproteinase 2, and vascular endothelial growth factor A. This is the first study to investigate the effects of both 3D culture and mechanical load on hASC osteogenic differentiation. A complete microarray analysis investigating both the separate effect of soluble osteogenic inductive factors and the combined effects of chemical and mechanical stimulation was performed on hASC undergoing osteogenic differentiation. We have identified specific genes and pathways associated with mechanical response and osteogenic potential of hASC, thus providing significant information toward improved understanding of our use of hASC for functional bone tissue engineering applications.

Modulation of collagen gel compaction by extracellular ATP is MAPK and NF-kappaB pathways dependent.

Understanding the mechanisms that regulate mechanosensitivity in osteoblasts is important for controlling bone homeostasis and the development of new drugs to combat bone loss. It is believed that prestress or force generation (the tensile stress within the cell body) plays an important role in regulating cellular mechanosensitivity. In the present study, a three-dimensional (3D) collagen culture was used to monitor the change in prestress of the osteoblast-like cells. Collagen hydrogel compaction has been used as an indicator of the change in the degree of cell prestress. Previous results in this model demonstrated that extracellular ATP reduced the mechanosensitivity of osteoblasts by reducing cellular prestress. To elucidate the potential mechanisms involved in this process, the signaling pathways downstream of P2 purinoceptors involved in regulating the compaction of type I collagen gels were investigated. By using specific inhibitors to these signaling pathways, we found that ATP-induced reduction in collagen gel compaction rate is dependent on mitogen-activated protein kinase (MAKP) and NF-kappaB pathways. However, blocking protein kinase C with GF109203X did not change the compaction kinetics in the presence of ATPgammaS. Moreover, blocking cyclic AMP (cAMP), phosphatidylinositol-3 kinase (PI3K), calmodulin (CaM) or L-type voltage sensitive calcium channels did not affect ATP's ability to reduce collagen gel compaction. The results from the present and previous studies indicate that extracellular ATP may act as a negative feedback modulator in the mechanotransduction system since mechanical stimuli increase ATP release from stimulated cells.

Effects of oxygen plasma treatment on adipose-derived human mesenchymal stem cell adherence to poly(L-lactic acid) scaffolds.

Plasma treatment of substrate surfaces can be utilized to improve adhesion of cells to tissue-engineered scaffolds. The purpose of this study was to enhance cell adhesion to non-woven poly(L-lactic acid) (PLLA) scaffolds using oxygen plasma treatment to increase surface hydroxyl groups and thereby enhance substrate hydrophilicity. It was hypothesized that oxygen plasma treatment would increase the number of adipose-derived human mesenchymal stem cells (hMSCs) that adhered to melt-blown, non-woven PLLA scaffolds without affecting cell viability. The number of cells that adhered to the oxygen plasma-treated (10 min at 100 W) or untreated PLLA scaffolds was assessed at 2, 4, 8, 12, 24 and 48 h post-seeding via DNA analysis. Cell viability and morphology were also assessed at 2, 4, 8, 12 and 24 h post-seeding via a live/dead assay and hematoxylin staining, respectively. Oxygen plasma treatment decreased the contact angle of water from 75.6 degrees to 58.2 degrees , indicating an increase in the surface hydrophilicity of PLLA. The results of the DNA analysis indicated that there was an increased number of hMSCs on oxygen plasma treated scaffolds for two of the three donors. In addition, oxygen plasma treatment promoted a more even distribution of hMSCs throughout the scaffold and enhanced cell spreading at earlier time points without altering cell viability. This early induction of cell spreading and the uniform distribution of cells, in turn, may increase future proliferation and differentiation of hMSCs under conditions that simulate the microenvironment in vivo.

Effects of serial passaging on the adipogenic and osteogenic differentiation potential of adipose-derived human mesenchymal stem cells.

Adipose-derived human mesenchymal stem cells (hMSCs) will be more valuable for tissue engineering applications if they can be extensively subcultured without loss of phenotype and multilineage differentiation ability. This study examined the effects of serial passaging on growth rate, gene expression, and differentiation potential of adipose-derived hMSCs. Differentiation was assessed by analyzing changes in messenger RNA (mRNA) expression of osteogenic and adipogenic marker genes and by determining production of calcium deposits and lipid vacuoles. Cells cultured in osteogenic medium for 2 weeks upregulated expression of alkaline phosphatase mRNA relative to cells in growth medium, and deposited calcium. Calcium deposition decreased in cells from passages 4 to 6 but returned to levels near or above those of primary cells by passage 10. Cells cultured in adipogenic medium upregulated expression of lipoprotein lipase and peroxisome proliferator activated receptor-gamma mRNA relative to cells in growth medium, and formed lipid vacuoles at all passages. By passage 8, however, cells in adipogenic medium also deposited calcium. Growth rate was stable through passage 5, then decreased. The results of this study indicate that adipose-derived hMSCs are capable of both adipogenic and osteogenic differentiation through 10 passages (34 population doublings) but that osteogenic differentiation may start to dominate at later passages.

Toxicity and efficacy of cisplatin and doxorubicin combination chemotherapy for the treatment of canine osteosarcoma.

Thirty-five dogs with appendicular osteosarcoma underwent amputation and chemotherapy with cisplatin and doxorubicin every 21 days for up to four cycles. Sixteen dogs completed all four cycles. Two dogs had therapy discontinued because of metastases. The remaining 17 dogs experienced toxicities necessitating protocol alteration or discontinuation. The median survival time of 300 days was not improved over previously reported single-agent protocols, but the 10 dogs that survived to a year lived a median of 510 days.