A method for delivering particles to a target location of a subject includes slidably disposing a polymeric carrier in a lumen of a catheter. The lumen extends in the catheter from a proximal opening to a delivery region. The method further includes inserting the delivery region of the catheter in the target location of the subject and forcing the particles through the lumen of the catheter to cause the carrier and the particles to exit the delivery region of the catheter. The particles may be cells or drug-loaded microspheres. The carrier can serve to retain the particles in the target location for a period of time. For treatment of vertebral disc degeneration, the particles can be stem cells, the carrier can be formed from collagen, and the target location can be the nucleus pulposus.