VAN KAMPEN UNIT TRUSTS, SERIES 821 TRUST AGREEMENT Dated: December 16, 2008 This Trust Agreement among Van Kampen Funds Inc., as Depositor, The Bank of New York Mellon, as Trustee, Van Kampen Asset Management, as Supervisor, sets forth certain...Trust Agreement • December 16th, 2008 • Van Kampen Unit Trusts Series 821
