Which of these is NOT a major step in Tissue Engineering?

In the context of tissue engineering, the processes involved typically include extraction of living cells, cell culturing, and implantation. Each of these steps is crucial for creating tissue constructs that can potentially be used in regenerative medicine.

Extraction of living cells is an initial step where cells are obtained from a donor or a patient. Following this, cell culturing is a process where these cells are grown and expanded in a controlled environment to reach the necessary quantity and viability for tissue formation. Ultimately, implantation involves transplanting the engineered tissue into a recipient, where it can integrate and function as part of the biological system.

Combining old cells with new cells is not considered a major step within standard tissue engineering protocols. While there may be interesting research surrounding the idea of co-culturing different cell types or the incorporation of existing cells in certain tissue engineering strategies, the primary focus remains on the effective extraction, culture, and implantation of living cells to create new tissue structures. Therefore, this option does not align with the basic framework of the major steps typically recognized in tissue engineering practices.