What a neat trike! The VeloPlus by Dutch company Van Raam allows for up to two riders, one that powers the bike and another that is sitting in a wheelchair toward the front of the trike.
In order to load the wheelchair and user, the bay platform pivots downward to create a ram. Then the wheelchair is pushed back onto the bay and it pivots back perpendicular to the ground. There is a strap (think safety belt) that is then brought up and over the wheelchair and rider. You can watch it in action here:
The trike has an option to come with an electric battery and is equipped with 8 speeds. The list price is 4095 euros or roughly $5500.
Check out this video of almost a whole family riding on trike!: