Methods and apparatus are provided for treating damaged tissue using apparatus that atraumatically deliver a bioactive agent within the tissue, wherein the apparatus provide a column of stem cells that may be advanced simultaneously with a needle during needle insertion, and then held stationary or injected at low pressure while retracting the needle. Alternatively, the needle may employ electromotive forces, or a dimension of the needle may be changed, to expel the bioactive agent into the needle track.
