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. Author manuscript; available in PMC: 2014 May 27.
Published in final edited form as: Methods. 2008 Oct 24;47(2):116–121. doi: 10.1016/j.ymeth.2008.10.013

Fig. 1.

Fig. 1

In vivo implantation of PEG hydrogel. PEG hydrogel was fabricated in four configurations: PEG alone, PEG with bFGF, microchanneled PEG, or both bFGF-adsorbed and microchanneled PEG. (A) PEG hydrogel molded into 6 × 4 mm (diameter × height) cylinder (without either bFGF or microchannels). (B) PEG hydrogel with three microchannels. (C) PEG hydrogel cylinder with adsorbed 0.5 mg/mL bFGF and three microchannels. Following in vivo implantation subcutaneously in the dorsum of immunodeficient mice, the harvested PEG hydrogel samples showed distinct histological features. (A1) PEG hydrogel with microchannels but without bFGF showed host tissue infiltration primarily in the lumen of microchannels, and scarcely in the rest of PEG hydrogel. The infiltrating host tissue includes erythrocyte-filled blood vessels that are lined by endothelial cells (arrow). (A2) VEGF was immunolocalized only to host-derived tissue within the lumen of microchannels, indicating the vascular nature of the infiltrating host tissue. Arrows point to microchannels and the infiltrating host tissue. (B1) PEG hydrogel with bFGF but without microchannels showed apparently random and isolated islands of infiltrating host tissue (arrow). The infiltrating host tissue includes vascular structures with erythrocyte-filled blood vessels that are lined by endothelial cells (arrow). (B2) VEGF was immunolocalized to host-derived tissue within PEG hydrogel (without microchannels). (C1) PEG hydrogel with both microchannels and bFGF showed host tissue infiltration only in the lumen of microchannels, but scarcely in the rest of the PEG hydrogel. The infiltrating host tissue includes vascular structures with erythrocyte-filled blood vessels that are lined by endothelial cells (arrow). (C2) VEGF was immunolocalized only to host-derived tissue within the lumen of microchannels. Since no cells were delivered in any of the PEG hydrogel samples, tissue infiltration following in vivo implantation is derived from the host. Arrows point to microchannels.