TABLE 1.

Experimental groups and preparation of freeze-drying solutions containing exosomes.

Experimental groups	Trehalose added	PVP40 added	Volume and strength of PBS	Exosomes added	Total volume
1X PBS (Control)	0.000 g	0.000 g	4 mL of 1X PBS	1 mL in 1X PBS	5 mL
50 mM Trehalose + 0.0% PVP40	0.095 g	0.000 g	4 mL of 0.83X PBS	1 mL in 1X PBS	5 mL
50 mM Trehalose + 2.5% PVP40	0.095 g	0.125 g	4 mL of 0.83X PBS	1 mL in 1X PBS	5 mL
50 mM Trehalose + 5.0% PVP40	0.095 g	0.250 g	4 mL of 0.83X PBS	1 mL in 1X PBS	5 mL
100 mM Trehalose + 0.0% PVP40	0.191 g	0.000 g	4 mL of 0.65X PBS	1 mL in 1X PBS	5 mL
100 mM Trehalose + 2.5% PVP40	0.191 g	0.125 g	4 mL of 0.65X PBS	1 mL in 1X PBS	5 mL
100 mM Trehalose + 5.0% PVP40	0.191 g	0.250 g	4 mL of 0.65X PBS	1 mL in 1X PBS	5 mL

To maintain the osmolality around 290 mOsm/kg, diluted PBS solutions at 0.83X and 0.65X strengths were used for preparation of 50 and 100 mM trehalose whereas PVP’s contribution is assumed to be negligible. To ensure the sterility, freeze-drying solutions containing trehalose and PVP were prepared in larger volumes and then sterile filtered before adding exosomes.