Why was bovine insulin used as the source of insulin?

Bovine insulin, derived from cattle pancreases, was historically used as the primary source of insulin for the treatment of diabetes due to several reasons:

Abundant Availability: Cattle are widely available for commercial livestock farming, making the extraction of insulin from their pancreases a feasible and practical option. The supply of bovine pancreases was more sufficient to meet the growing demand for insulin compared to other potential sources.

Extraction Methods: Early methods of insulin extraction were more efficient and well-established for bovine pancreas. Researchers had developed successful techniques to isolate and purify insulin from cattle pancreases effectively.

Structural Similarity: The structure of bovine insulin closely resembles the structure of human insulin. Both consist of two polypeptide chains, A and B, linked by disulfide bonds. This similarity allowed the therapeutic use of bovine insulin for patients with diabetes without substantial species-specific immune reactions.

Lower Immune Responses: Compared to insulin derived from other animal sources, such as porcine pancreases, bovine insulin generally demonstrated a lower potential for inducing immune reactions in human recipients. Some patients experienced an initial immune response, but in many cases, the immune system would become tolerant over time.

However, in recent years, the discovery of synthetic human insulin in the 1970s and the improvement of recombinant DNA technology led to the availability of genetically engineered human insulin. Due to the potential for reduced immune reactions and better adherence to human physiology, human insulin gained prominence and dominance, eventually replacing bovine insulin as the primary source of insulin therapy for diabetes.