In rats with a muscle injury, researchers saw two kinds of immune cells (macrophages) that help heal the tissue. One type cleans up debris, the other releases signals to guide repair. Adding immunomodulating substances made the cells' internal structures develop faster, which seemed to speed up healing, but the study gives no details on what to use in people.

The electron transmission microscopy was used for studying the ultrastructure of macrophages involved in the reparative regeneration of skeletal muscles of Wistar rats after a mechanical injury. Two morphofunctional types were established with special reference to ultrastructural features of the macrophages and morphometrical characteristics of organelles of these cells. The first type includes macrophages with a strong lysosomal apparatus and great amount of phagosomes containing a muscular dendritis. They are responsible for phagocytic functions and facilitate debridement of the wound from tissue disintegration products. The second (secretory) type is the cells with the developed granular endoplasmic reticulum which can exert a regulatory influence on processes of reparative regeneration of the skeletal muscles. Immunomodulators influence the level of the development of organelles of both types of macrophages which facilitates the earlier development of regeneration processes and wound healing.