Tissue-engineered and regenerative medicine products are promising innovative therapies that can address unmet clinical needs. These products are often combinations of cells, scaffolds, and other factors and are complex in both structure and function. Their complexity introduces challenges for product developers to establish novel manufacturing and characterization techniques to ensure that these products are safe and effective prior to clinical trials in humans. Although there are only a few commercial products that are currently in the market, many more tissue-engineered and regenerative medicine products are under development. Therefore, it is the purpose of this article to help product developers in the early stages of product development by providing insight into the Food and Drug Administration (FDA) process and by highlighting some of the key scientific considerations that may be applicable to their products. We provide resources that are publically available from the FDA and others that are of potential interest. As the provided information is general in content, product developers should contact the FDA for feedback regarding their specific products. Also described are ways through which product developers can informally and formally interact with the FDA early in the development process to help in the efficient progression of products toward clinical trials.
The interaction of mouse macrophages with influenza virus was examined as part of a study into the defense mechanisms against influenza infection. Macrophages exposed to A/Port Chalmers/1/73 virus produced infectious foci on susceptible indicator cell monolayers. Sampling of supernatant fluids and cells from infected macrophage cultures showed release of virus adsorbed to the cell surface. Active virus replication in macrophages could not be demonstrated. Exposing macrophages to specific antibody before or after virus infection resulted in a significant decrease in the number of infectious macrophages. The results suggest that although macrophages are not the source of replicating influenza virus, they are able to spread the infection by having virus attaching to their surface. This activity is interfered with by the presence of specific antibody.
Infectivity of human T-cell lymphotropic virus, Type III (HTLV-III) was inactivated by heat more rapidly if in liquid medium than if lyophilized and more rapidly at 60 degrees than 56 degrees C. When HTLV-III was added to factor VIII suspension, then lyophilized and heated at 60 degrees C for 2 hours or longer there was elimination of 1 X 10(6) in vitro infectious units (IVIU) of virus. Much of the viral inactivation appeared to result from lyophilization. The application of water-saturated chloroform to the lyophilized material containing virus also resulted in elimination of infectivity. HTLV-III was efficiently inactivated by formalin, beta-propiolactone, ethyl ether, detergent, and ultraviolet light plus psoralen. The results are reassuring regarding the potential safety of various biological products.
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