Aims: Calcitonin is a small peptide hormone that is produced by parafollicular thyroid cells in human and regulates the metabolism of calcium and phosphorus. It is therapeutically used in treatment of calcium-related disorders and osteoporosis. Recombinant calcitonin production encounters with several difficulties due to instability and low molecular weight, and also needs further treatment in prokaryotic systems. Microalgae have recently garnered high attention for their potential in expression of recombinant proteins. The aim of present study was to assess the ability of Chlamydomonas Reinhardtii to express recombinant human calcitonin.
Materials & Methods: The optimized calcitonin coding sequence and carbonic anhydrase secretory signal was cloned in Pchlamy­_3 and Pchlamy_4 vectors. The recombinant plasmids were transformed to wild type and also a cell wall deficient strain of Chlamydomonas Reinhardtii by electroporation. Transformed strains were screened by colony PCR method and selected strains were cultivated to produce recombinant calcitonin. Culture media have been collected after cells growth and assayed by ELISA method.
Findings: Pchlamy_3 vector could not express the target sequence as desired and all the recombinant strains were resulted from Pchlamy_4 vector. The wild type strain also did not show desired yield and only cell wall deficient strain was successfully transformed. The yield of recombinant calcitonin produced by positive strain was about 1 pg/ml.
Conclusion: The results of this study show that the used strategy for secretory production of recombinant calcitonin was successful and it could be used in further studies.
 

Microalgae are microscopic algae found in a wide range of habitats including freshwater and marine systems. Over the last decades, biotechnological processes based on microalgae have been receiving increasing interest due to their potential to produce large quantities of valuable products used as human food supplements, pharmaceuticals and animal feed. Microalgae have also been proved as an efficient and cost-effective platform for recombinant protein production. Most progress in this field has been achieved using Chlamydomonas reinhardtii, a photosynthetic unicellular alga which has been mostly considered as a model organism in different studies. High growth rate, ease of cultivation, well-established genetics and the ability to perform post-translational modifications are the most beneficial attributes that have made C. reinhardtii an attractive system for the expression of recombinant proteins. In this review, we focus on C. reinhardtii as a novel platform for the development of advanced recombinant products and compare them with other commonly used expression systems. We also present a comprehensive overview of its structure, life cycle, culture systems, and media in detail and then discuss the strategies for engineering its three different genomes to produce recombinant cells. Finally, algal culture collections in the world are introduced.