A tissue puncture closure assembly including a wire assembly and a sealing pad delivery device, The wire assembly includes a proximal end portion, a distal end portion, and a temporary expandable anchor positioned at the distal end portion. The sealing pad delivery device includes a carrier tube, a sealing pad positioned in the carrier tube, and a lateral wire slot. The lateral wire slot is defined in an outer surface of the sealing pad delivery device and extends along at least a portion of a length of the sealing pad delivery device. The lateral wire slot is configured to permit mounting of the sealing pad delivery device to the wire assembly in a lateral direction.

Apparatus for sealing a vascular wall penetration disposed at the end of the tissue tract comprises a shaft, an optional occlusion element, a hydratable hemostatic implant, and a protective sleeve. The apparatus is deployed through the tissue tract with the occlusion element optionally occluding the vascular wall penetration and inhibiting backbleeding therethrough. The hydratable hemostatic implant, which will typically be a biodegradable polymer such as collagen carrying an anti-proliferative agent or coagulation promoter, will then be deployed from the sealing apparatus by retracting the protective sleeve and left in place to enhance closure of the vascular wall penetration with minimum scarring. The hydratable implant will be protected from premature hydration and swelling by a soluble plug covering the implant's distal end prior to sleeve retraction.