Micro/Nanobubbles: A Novel Oxygenation Technology for Cellular and Organ Transplantation

Purpose:

The survival and preservation of transplanted tissue (kidney, heart, fat grafts) are directly tied to and limited by ischemia time. A new innovation, micro/nanobubbles (MNBs), are miniature gaseous voids that allow for oxygenation of a tissue bathed in them for varying periods of time¹. Given their high oxygen carrying capacity, MNBs offer an inexpensive technology for oxygenating transplantable tissue and improving cell survival and viability. A priority in the field of islet cell transplantation for Type 1 Diabetes is to preserve every single islet count due to the shortage of donors and consistent low recovery of islets with current isolation procedures^2,3. The purpose of this study was to demonstrate that islet cell survival and viability can be improved when immersed in MNBs and to generalize our findings to other autologous and allogenic transplants. 

Materials & Methods:

Rat pancreatic islet cells were harvested and split into 3 groups starting with 500 cells in each group – these were cultured in JPI media overnight. On day 0, media was changed to either control media (pO₂: 210 mmHg); control media with dissolved air (pO₂: 210 mmHg) or micro/nanobubbled solution (pO₂: 223 mmHg). Media was replenished under the same conditions at 24 hours. On day 2 the number of living islet cells were counted using dithizone staining and their viability was assessed using the calceinAM/propidium assay. All experiments were replicated 5 times to achieve statistical significance.

Data:

Islet cells preserved in air filled micro/nanobubbled solutions had both a significantly improved cell survival and viability (Islet count: 223, viability: 96±1%) when compared to either islet cells treated with control media (Islet count: 104, viability: 87±1%) or control media with dissolved air (Islet count: 92, viability: 87±1%).

Summary of Results:

Harvested Islet cells preserved in MNB solution had a significant improvement in cell survival and viability when compared to the controls. MNBs improve Islet survival by 114% (223 cells vs. 104 cells) and viability by 10% (96% vs. 87%).

Conclusions:

MNBs added to standard media significantly improve oxygenation and survival of harvested pancreatic islet cells prior to transplantation compared to control media. These findings are very encouraging in the field of islet cell transplantation for Type 1 diabetes given the demonstrated increase in preservation of robust cells. Given these findings, we hypothesize that MNBs may also improve oxygenation and survival of a variety of other tissues including fat grafts from lipoaspirate, chronic wounds and large organs.  

References:

1. Sayadi LR BD, Ziegler ME, et al. . Topical Oxygen Therpay & micro/nanobubbles: a new modality for tissue oxygen delivery. International wound journal. 2017:1-13
2. Barshes NR, Wyllie S, Goss JA. Inflammation-mediated dysfunction and apoptosis in pancreatic islet transplantation: implications for intrahepatic grafts. J Leukoc Biol. 2005;77(5):587-597.
3. Ricordi C, Strom TB. Clinical islet transplantation: advances and immunological challenges. Nat Rev Immunol. 2004;4(4):259-268.