The development of tissue engineering medical products is co

The development of tissue engineering medical products is complex since it poses challenges in both basic biology and engineering. Before devoting time and resources to a new product, it often useful to quickly estimate parameters involved with the problem to more fully understand the problem and the issued that need to be addressed to make a clinically effective product. 1. For tissue graft application, consider two different types of tissue, cartilage and skin. For a defect of 5cm3, estimate:

a. The number or cells needed to repair a defect

b. The number of cells needed prior to ex vivo expansion to achieve this therapeutic number of cells

c. The time it would take to start with the minimum number of cells and to end with final therapeutic cell number assuming a doubling time of 36 hours for chondrocytes and 15 hours for fibroblasts. Assume normal cell density for cartilage is 1 million cells/cm3 and fibroblasts is 200 million cells/cm3.

Solution

1.

Chondrocytes having size of 20u or 20 x10^-6 cm. therefore, 5cm³ size would have 5 x (20^-1 x 10⁶)³ cells.

= 5 x 8000^-3x 10¹⁸ cells = 5/8 x 10¹⁵ cells. Fibroblast cells are double of it.

2.

Ex-vivo-expansion needs at least 10 times more cells before implantation.