Thermal Regulation of Human Mesenchymal Stem Cell Differentiation toward Bone and Cartilage Lineages
Item
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Title
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Thermal Regulation of Human Mesenchymal Stem Cell Differentiation toward Bone and Cartilage Lineages
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Identifier
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d_2009_2013:31a8a7f10f8d:11641
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identifier
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12235
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Creator
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Chen, Jing,
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Contributor
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Sihong Wang
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Date
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2013
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biomedical engineering
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Abstract
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In USA alone, osteoarthritis affects about 70 million people and over 65 billion dollars are spent each year to treat the disease and related conditions. The late stage of joint repair in arthritis patients usually requires to regenerate both cartilage and bone tissues. Human mesenchymal stem cells (hMSCs) are multipotent. Human MSCs seeded with bioengineered scaffolds, combined with growth factors and/or mechanical stress during osteogenesis and chondrogenesis have been intensively studied. However, despite these efforts, the osteoblasts and chondrocytes differentiated from hMSCs are still not as functionally mature as primary adult cells. Thermal regulation of hMSC differentiation may be one of the missing aspects that need to be investigated in terms of further maturation and optimization.;In this study, the direct effects of mild heat shock (HS) on the differentiation of hMSCs into osteoblasts and chondrocytes in self-assembling peptide hydrogel were investigated. Periodic HS at 41°C for 1 hr significantly increased the alkaline phosphatase (ALP) activity and calcium deposition in osteogenic cultures and upregulated osteo-specific genes such as osterix, osteopontin, BMP2 and Runx2. Heat shock protein (HSP) 27, 70 and 90 were also evaluated during differentiation and HSP70 expression was upregulated via heat shock.;For chondrogenic cultures, biochemical analyses showed that periodic HS significantly increased sGAG content at early stage of differentiation in both 3D pellet and hydrogel cultures at Day 10 and 17 respectively. Immunohistochemical (IHC) analyses revealed a more intense staining of chondroitin sulfate proteoglycan in heatshocked pellets than non heat-shocked pellets on Day 17, but weaker staining of collagen type II on Day 24 in heat treated samples. In summary, these results demonstrate that HS induced a faster differentiation of hMSCs and enhanced the maturation of osteoblasts and chondrocytes differentiated from hMSCs in the early stage. The further maturation of chondrocytes from hMSCs by HS might lead to hypertrophic chondrogenesis. The decrease of chondrogenic markers at late days might correlate with the phenomena similar to the process during endochondral ossification in vivo..;The potential of using low-intensity pulsed ultrasound (LIPUS) as a clinically relevant tool to deliver thermal stimulus to hMSCs was investigated. A custom-made LIPUS device with either focused or plane-wave ultrasound transducers was developed to apply heat to hMSCs cultured in a 12-well cell culture plate. A temperature measurement system with thermistors controlled by LabVIEW was built. A hydrophone was used to calibrate the ultrasound intensity distribution. Parameters such as, acoustic intensity (mW/cm2), duty cycle, and pulse repetition frequency of the input signal were adjusted to achieve the temperature rise in cell culture wells. Further work will be conducted in the future to study thermal effects of ultrasound on hMSC osteogenesis and chondrogenesis. The study will guide the design of an US device for in vivo thermal treatments in bone and cartilage regeneration.
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Type
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dissertation
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Source
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2009_2013.csv
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degree
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Ph.D.
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Program
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Engineering
