​

​

December 31, 

​

2020

2019

Accrued interest expense

​

$

34

​

$

4,708

Accrued property and equipment purchases

​

3,992

​

—

Accrued research and development costs

​

2,420

​

2,195

Accrued professional fees

​

​

1,386

​

​

160

Accrued Business Combination costs

​

​

815

​

​

—

Short term lease liability

​

444

​

368

Other accrued expenses

​

1,534

​

703

Total accrued expenses

​

$

10,625

​

$

8,134