4. Property and Equipment, net

Property and equipment, net consisted of the following:

 

		December 31,
		2015				2014
Equipment		$	3,359			$	2,606
Leasehold improvements			894				815
Furniture and fixtures			403				295
Software			54				25
Construction in progress			1,324				262
			6,034				4,003
Less: Accumulated depreciation			(2,939	)			(2,221	)
		$	3,095			$	1,782

Depreciation expense was $754, $547 and $404 for the years ended December 31, 2015, 2014 and 2013, respectively.

The construction in progress is related to the build-out of an aseptic manufacturing suite clean room.