This study explored the possibility of freeze-drying human bone marrow tissue.
For freezing, tissue was cut to slices of size of 1mm x 10mm x 10mm or smaller. These slices were then exposed to a LYO solution composed of CPs and sugars in a holding buffer medium for an exposure time of 5 to 10 minutes, placed on a carrier or inside a straw having a special pod, plunged into LN or sterile liquid air using FertileSafe’s CLAir device, and then placed into the LyoLife bench top device for primary and secondary drying. Primary drying was conducted at a high sub-zero temperature, slightly lower than the Tg’ of the LYO solution used. Secondary drying was then conducted by increasing the shelf temperature in a step-wise manner. Finally rehydration was achieved by removing the carriers containing the tissue slices and immersed into a warm solution.
A confocal microscopy (live/dead staining) of fresh and freeze-dried bone marrow tissue indicated 78% live cells for fresh bone marrow tissue vs. 45% for freeze dried bone marrow tissue that had been stored at room temperature for 24 hours.
The research indicates that freeze-dried bone marrow tissue retains viability, although further R&D investment is required to improve results.
Figure 1: Confocal microscopy of human dry bone (live/dead staining)
Left = Fresh with 78% cell viability
Right = Freeze-dried with 45% cell viability after 24 hours at room temperature
Figure 2: Bone cells in culture derived from freeze-dried human bone chips