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Research Papers

Fabrication of Cell-Encapsulated Alginate Microfiber Scaffold Using Microfluidic Channel

[+] Author and Article Information
Byung Kim

Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Kyungbuk 790-784, South Koreacleareye@postech.ac.kr

Intae Kim

Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Kyungbuk 790-784, South Koreaone@postech.ac.kr

WooSeok Choi

Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Kyungbuk 790-784, South Koreadalton@postech.ac.kr

Sung Won Kim

Department of Otolaryngology-HNS, Catholic University of Korea College of Medicine, Seoul 150-712, South Koreakswent@catholic.ac.kr

JooSung Kim

Department of Orthopedic Surgery, HyunDae General Hospital, Daegu, 706-050, South Koreaspinekim@chol.com

Geunbae Lim

Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Kyungbuk 790-784, South Korealimmems@postech.ac.kr

J. Manuf. Sci. Eng 130(2), 021016 (Apr 09, 2008) (6 pages) doi:10.1115/1.2898576 History: Received September 23, 2007; Revised February 20, 2008; Published April 09, 2008

Traditional approaches in tissue engineering are limited in that cell seeding is inefficient and cells cannot be located on a scaffold precisely. Moreover, the traditional methods, which rely on a random and probabilistic process, produce scaffolds with low regularity in porosity, pore size, and interconnection of pores. In this research, we propose a novel method to fabricate a scaffold for tissue engineering, which can overcome the limitations of traditional approaches. Cell-encapsulated alginate solution and cross-linker solution were laminarly flowed into a microfluidic channel. Then, the alginate solution was gelled to form a cell-encapsulated alginate microfiber by the diffusion of gelation ion from the cross-linker solution and ejected from the outlet of channel to the reservoir. The diameter of the fabricated microfiber can be controlled by the flow rate ratio of the two solutions. Moreover, this method, which has no cell seeding step, eliminates the possibility of loss of cells and the problems related to distribution of cells. We also show the feasibility of the alginate microfiber as a scaffold, which can promote chondrogenesis. The chondrogenesis in the alginate microfiber was evaluated by both histological and biochemical analyses. The increase of major markers of chondrogenesis such as glycosaminoglycan and collagen shows the potential of alginate microfiber as a scaffold for cartilage.

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Copyright © 2008 by American Society of Mechanical Engineers
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Figures

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Figure 1

Flowchart of MEMS processes. Microfluidic channels were fabricated using two MEMS techniques: DRIE (a) and soft lithography (b).

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Figure 2

Schematic of fabrication of alginate microfiber using microfluidic device

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Figure 3

Hydrodynamic focusing and gelation of alginate solution. Alginate solution was hydrodynamically focused at the t-junction of the microchannel (a) and gelled in the gelation region (b). One droplet (less than 5% of total volume) of color ink was mixed with the alginate solution to visualize it.

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Figure 4

The fabricated alginate microfiber. (a) Microfiber folded and fluctuated during ejection. (b) The cross section of the microfiber is circular. The nonwovenlike microfiber was observed by optical microscope (c) and SEM (d).

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Figure 5

The linewidth of the microfiber with respect to the flow rate ratio. When 100μl∕min of the alginate core flow passed through a 500×300μm2 microchannel, the linewidth of the fabricated microfiber ranged from about 138μmto185μm. As the flow rate ratio was increased, the resultant linewidth of the microfiber increased: (a) ratio=2, width=185μm, (b) ratio=3, width=164μm, (c) ratio=4, width=150μm, and (d) ratio=5, width=138μm.

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Figure 6

The linewidth of the microfiber with respect to the flow rate ratio. When 100μl∕min of the alginate core flow passed through a 500×300μm2 microchannel, the linewidth of the fabricated microfiber ranged from about 138μmto185μm. As the flow rate ratio was increased, the resultant linewidth of the microfiber increased: (a) ratio=2, width=185μm, (b) ratio=3, width=164μm, (c) ratio=4, width=150μm, and (d) ratio=5, width=138μm.

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Figure 7

Alcian blue staining of chondrocytes in alginate microfiber at (a) 1week, (b) 2weeks, (c) 4weeks, and (d) 6weeks. The original magnification is ×400.

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Figure 8

Masson’s trichrome staining of chondrocytes in the alginate microfiber at (a) 1week, (b) 2weeks, (c) 4weeks, and (d) 6weeks (d). The original magnification is ×400.

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Figure 9

GAG content. GAG content increases steeply until 2weeks. However, after then, the level of the GAG content barely increases and is saturated.

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