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postgraduate thesis: Pushing stem cells toward bone lineage through ultrasound stimulation
Title | Pushing stem cells toward bone lineage through ultrasound stimulation |
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Authors | |
Advisors | |
Issue Date | 2011 |
Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
Citation | Poon, C. [潘展豪]. (2011). Pushing stem cells toward bone lineage through ultrasound stimulation. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b4784982 |
Abstract | When human mesenchymal stem cells (hMSCs) are cultured inside a 3D collagen meshwork, they become a potential tissue engineering bone graft alternative. However, the in vitro osteogenesis rate of hMSCs is slow, leading to a low mineral deposition.
To enhance the osteogenic differentiation of hMSCs, low intensity pulsed ultrasound (LIPUS) was employed as an external stumulus. The present study demonstrated the feasibility of employing daily LIPUS exposure for enhancing osteogenesis in vitro. Exposure of seven consecutive days LIPUS, each of 30 minutes duration, did not affect the cell viability, and the organization of hMSCs within the collagen meshwork was not disturbed. The calcium deposition within the collagen meshwork was enhanced after seven days of exposure. The osteoinductivity was also upregulated at the early period of culture.
In order to optimizing the enhancement effects of LIPUS, various ultrasound parameters, including intensity, exposure duration and exposure repetition were investigated. Results showed the LIPUS enhancement effects are dose dependent, LIPUS exposure should be longer than 10 minutes/day in order to elicit a significant effect. Calcium deposition was higher when LIPUS exposure was done twice per day instead of one. Although individual variation exists, optimal LIPUS intensity range was between 60-120 mW/cm2 ISATA (Spatial Average Temporal Average Intensity).
The interaction mechanism between LIPUS and cells was also investigated. Microbubbles were added to the culture during LIPUS exposure to find out whether cavitation is involved in the interaction. Flow sensor primary cilium was also studied in order to verify that ultrasound is transduced through fluid flow. Results showed cavitation may not be a contributing factor to osteogenesis, and primary may be involved in the transduction of LIPUS stimulation.
This study demonstrated that osteogenesis of hMSCs encapsulated in collagen constructs could be enhanced by LIPUS. The LIPUS parameters were also optimized. The LIPUS interaction pathways were also being better understood. This thesis study will be a paradigm for cellular mechanotransduction studies and put an important step forward for therapeutic ultrasound. |
Degree | Master of Philosophy |
Subject | Stem cells - Therapeutic use. Bones - Growth. Ultrasonics in medicine. |
Dept/Program | Electrical and Electronic Engineering |
Persistent Identifier | http://hdl.handle.net/10722/174540 |
HKU Library Item ID | b4784982 |
DC Field | Value | Language |
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dc.contributor.advisor | Yu, ACH | - |
dc.contributor.advisor | Chan, BP | - |
dc.contributor.author | Poon, Chin-ho. | - |
dc.contributor.author | 潘展豪. | - |
dc.date.issued | 2011 | - |
dc.identifier.citation | Poon, C. [潘展豪]. (2011). Pushing stem cells toward bone lineage through ultrasound stimulation. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b4784982 | - |
dc.identifier.uri | http://hdl.handle.net/10722/174540 | - |
dc.description.abstract | When human mesenchymal stem cells (hMSCs) are cultured inside a 3D collagen meshwork, they become a potential tissue engineering bone graft alternative. However, the in vitro osteogenesis rate of hMSCs is slow, leading to a low mineral deposition. To enhance the osteogenic differentiation of hMSCs, low intensity pulsed ultrasound (LIPUS) was employed as an external stumulus. The present study demonstrated the feasibility of employing daily LIPUS exposure for enhancing osteogenesis in vitro. Exposure of seven consecutive days LIPUS, each of 30 minutes duration, did not affect the cell viability, and the organization of hMSCs within the collagen meshwork was not disturbed. The calcium deposition within the collagen meshwork was enhanced after seven days of exposure. The osteoinductivity was also upregulated at the early period of culture. In order to optimizing the enhancement effects of LIPUS, various ultrasound parameters, including intensity, exposure duration and exposure repetition were investigated. Results showed the LIPUS enhancement effects are dose dependent, LIPUS exposure should be longer than 10 minutes/day in order to elicit a significant effect. Calcium deposition was higher when LIPUS exposure was done twice per day instead of one. Although individual variation exists, optimal LIPUS intensity range was between 60-120 mW/cm2 ISATA (Spatial Average Temporal Average Intensity). The interaction mechanism between LIPUS and cells was also investigated. Microbubbles were added to the culture during LIPUS exposure to find out whether cavitation is involved in the interaction. Flow sensor primary cilium was also studied in order to verify that ultrasound is transduced through fluid flow. Results showed cavitation may not be a contributing factor to osteogenesis, and primary may be involved in the transduction of LIPUS stimulation. This study demonstrated that osteogenesis of hMSCs encapsulated in collagen constructs could be enhanced by LIPUS. The LIPUS parameters were also optimized. The LIPUS interaction pathways were also being better understood. This thesis study will be a paradigm for cellular mechanotransduction studies and put an important step forward for therapeutic ultrasound. | - |
dc.language | eng | - |
dc.publisher | The University of Hong Kong (Pokfulam, Hong Kong) | - |
dc.relation.ispartof | HKU Theses Online (HKUTO) | - |
dc.rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works. | - |
dc.rights | This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. | - |
dc.source.uri | http://hub.hku.hk/bib/B47849824 | - |
dc.subject.lcsh | Stem cells - Therapeutic use. | - |
dc.subject.lcsh | Bones - Growth. | - |
dc.subject.lcsh | Ultrasonics in medicine. | - |
dc.title | Pushing stem cells toward bone lineage through ultrasound stimulation | - |
dc.type | PG_Thesis | - |
dc.identifier.hkul | b4784982 | - |
dc.description.thesisname | Master of Philosophy | - |
dc.description.thesislevel | Master | - |
dc.description.thesisdiscipline | Electrical and Electronic Engineering | - |
dc.description.nature | published_or_final_version | - |
dc.identifier.doi | 10.5353/th_b4784982 | - |
dc.date.hkucongregation | 2012 | - |
dc.identifier.mmsid | 991033486989703414 | - |