2 . It all began with an experience one of us (Arinzeh) had more than two decades ago. In 1991, a summer research experience at the University of California at Berkeley demonstrated how engineering could improve the lives of patients. Instead of working in a more traditional area such as automobile design, Arinzeh spent the summer after her junior year of college working in a rehabilitation laboratory.
Engineers there were designing new prosthetic (修复的) devices for patients who had lost limbs, and new assistive devices to help paralyzed patients move. The engineers would then collaborate with clinicians at a rehabilitation center to test their developments. Before that summer she hadn’t connected traditional engineering principles with the opportunity to solve biomedical problems. But by the end of those short months, Arinzeh was hooked on the promise of using mechanical engineering to help people move better.
Tissue engineering, a budding field at that time, offered a chance to move beyond building prosthetics. Damage to musculoskeletal tissues, such as bone and cartilage, and nervous tissue, such as the spinal cord, can be debilitating and can severely limit a person’s quality of life. In addition, such tissues cannot fully regenerate after a severe injury or in response to disease. Tissue engineers aim to fully repair and regenerate that tissue so that it regains complete function, but at that time researchers still had a lot to learn about cells and their support structures to solve these problems.
The earliest successes were with skin, in which researchers used dermal cells to generate grafts, leading to the first commercial products in the late 1990s. Researchers imitate nature, using cells as building blocks and developing strategies to guide the cells to form the appropriate tissue. Because stem cells (干细胞) are precursor (前身) to almost all tissue types, such cells are a promising source of these critical building blocks. But cells don’t grow and differentiate on their own. The cell’s microenvironment can influence stem-cell function in critical ways. Engineered microenvironments, or scaffolds, can effectively promote stem cells and other cell types to form tissues. To construct such scaffolds, some important tools are what are called functional biomaterials. These materials respond to environmental changes such as PH, enzymatic activity, or mechanical load, and their composition can mimic or replicate components of native tissue.
One of us (Arinzeh) wanted to use functional biomaterials to create three-dimensional tissue-like structures where cells can grow, proliferate (增殖), and differentiate, ultimately forming and regenerating tissue. Our group’s work started with bone studies in the 1990s, eventually moving into cartilage and the spinal cord over the past decade. The overall goal is to produce structures that could someday help patients struggling with severe injuries and movement disorders to move freely. For bone repair, our group has studied composite scaffolds consisting of polymers and ceramics that provide both mechanical and chemical cues to repair bone. Piezoelectric materials, which respond to mechanical stimuli by generating electrical activity, are used to encourage the growth of nerve tissue as well as cartilage and bone. Glycosaminoglycans (GACs), a major component of native cartilage tissue, provide growth factors to promote tissue formation, and Arinzeh has designed biomimetic scaffolds that incorporate these molecules. After all these years, the promise that seemed so enticing in 1991 is becoming a practical reality, with huge implications for human health.
1. Which of the following statements is TRUE?
| A．Before working with patients, Arinzeh was an automobile designer. |
| B．Since 1991, tissue engineering has been mainly applied to building prosthetics. |
| C．It’s hard for musculoskeletal tissues to fully recover from disease or injury. |
| D．In the late 1990s, the lack of knowledge about cells and their support structures prevented researchers from making any achievement in tissue engineering. |
2. The underlined word “differentiate” is close in meaning to ________.
| A．change | B．divide | C．alternate | D．reproduce |
3. “Scaffolds” are, in essence, ________.
| A．tissues from one part of a person’s body used to repair another damaged part |
| B．stem cells and other cell types in an engineered microenvironment |
| C．structural support for damaged tissue repair |
| D．functional biomaterials to replace native tissues. |
4. What can we learn about the study introduced above?
| A．It was inspired by the team members’ internship. |
| B．So far, the study has covered multiple musculoskeletal tissues, including bone, cartilage and nervous tissues. |
| C．The electrical activity caused by Piezoelectric materials will generate mechanical stimuli that encourage the growth of musculoskeletal tissues. |
| D．The researchers of this study are the best designers of modern tissue engineering. |
