人造血管可促进移植组织的研究

Researchers from Rice University and Baylor College of Medicine (BCM) have broken one of the major roadblocks（路障，障碍） on the path to growing transplantable tissue in the lab: They've found a way to grow the blood vessels¹ and capillaries²（毛细血管） needed to keep tissues alive. The new research is available online and due to appear in the January issue of the journal Acta Biomaterialia.

"The inability to grow blood-vessel networks -- or vasculature（脉管系统） -- in lab-grown tissues is the leading problem in regenerative medicine today," said lead co-author Jennifer West, department chair and the Isabel C. Cameron Professor of Bioengineering at Rice. "If you don't have blood supply, you cannot make a tissue structure that is thicker than a couple hundred microns." #

As its base material, a team of researchers led by West and BCM molecular³ physiologist⁴ Mary Dickinson chose polyethylene glycol (PEG⁵聚乙二醇), a nontoxic plastic that's widely used in medical devices and food. Building on 10 years of research in West's lab, the scientists modified the PEG to mimic⁶ the body's extracellular matrix（细胞外基质） -- the network of proteins and polysaccharides（多糖） that make up a substantial portion of most tissues.

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West, Dickinson, Rice graduate student Jennifer Saik, Rice undergraduate Emily Watkins and Rice-BCM graduate student Daniel Gould combined the modified PEG with two kinds of cells -- both of which are needed for blood-vessel formation. Using light that locks the PEG polymer strands⁷ into a solid gel, they created soft hydrogels（水凝胶） that contained living cells and growth factors. After that, they filmed the hydrogels for 72 hours. By tagging each type of cell with a different colored fluorescent⁸（荧光的） marker, the team was able to watch as the cells gradually formed capillaries throughout the soft, plastic gel. #

To test these new vascular⁹ networks, the team implanted the hydrogels into the corneas（角膜） of mice, where no natural vasculature exists. After injecting a dye into the mice's bloodstream, the researchers confirmed normal blood flow in the newly grown capillaries.

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Another key advance, published by West and graduate student Joseph Hoffmann in November, involved the creation of a new technique called "two-photon lithography（平版印刷术） ," an ultrasensitive way of using light to create intricate three-dimensional patterns within the soft PEG hydrogels. West said the patterning technique allows the engineers to exert a fine level of control over where cells move and grow. In follow-up experiments, also in collaboration#p#分页标题#e#¹⁰ with the Dickinson lab at BCM, West and her team plan to use the technique to grow blood vessels in predetermined patterns.