The club's sporting director has emphasised the importance of the Germany international, and was pleased with the defender's decision to pen a new deal
The 24-year-old defender penned a new deal on Friday, and the sporting director believes the Germany international perfectly reflects the Bundesliga champions' footballing ideals.
"Marcel is an important component of what is still a young team," Zorc was quoted as saying on the club's official website.
"He reflects BVB's philosophy to continue the path we're on with the core of this promising and identity-promoting team."
Schmelzer is a product of the Magdeburg youth academy, but has become a key figure at Dortmund since joining the club in 2005.
He has made 15 Bundesliga appearances so far this season.