Up to now, we’ve successfully obtained transformed P. aeruginosa expressing our antigenic peptides as T3SS effectors. To make our aim bacteria the form more suitable for therapeutic use, we decided to prepare them into freeze-dried powder as filler of capsules. One more thing we must take account of is that since we’re aiming at colorectal cancer (CRC), the drug must be released in the small intestine. So we have to find an enteric capsule shell, which is acid-resistant and merely soluble in the small intestine, to protect our therapeutic bacteria from being destroyed by gastric acid. After consulting Shanghai Roche Pharmaceuticals Ltd. and comprehensive web searching, we finally decided on one product of Suzhou Capsugel ® Ltd., DRcapsTM. According to the instructions of DRcapsTM, it bears at least the following merits that suit our project well:
It provides effective protection for acid-vulnerable ingredient in low-pH environment.
It has lower water content, thus providing better protection for hygroscopic drug components.
Made of plant-source hypromellose, it is also applicable for vegetarians and religious people.
We found that SJTU-BioX-Shanghai was also in search of enteric capsules for their own project, and that they knew well how to make freeze-dried powder. So we communicated to reach an agreement that we would provide them with reliable capsule shells and they help us prepare our bacterium freeze-dried powder in return. On 15th October, we trafficked empty DRcapsTM capsules and aim bacteria stored in liquid medium to Shanghai Jiaotong University. There, we were glad to see our P. aeruginosa turn into dried, pinky powder. Later, we filled it into empty capsule shells carried with us in biosafety cabinet. We sincerely appreciate iGEMers and teachers of SJTU for their generous help.
Owing to limitation of time, we haven’t yet figured out what kinds of adjuvant fit our therapy best. However, during our visit to Shanghai Roche Pharmaceuticals Ltd. last month, the company promised that we could contact their Research and Development Department for further discussion on adjuvants and form design if any requirement.