tissue engineering and tissue and organ regeneration application_number US 90178601 A description it is believed that mesenchymal cells such as dermal fibroblasts or fibroblasts from any other fetal neonatal or adult source of any age may harbor stem cell populations capable of differentiating or transdifferentiating into multiple cell phenotypes if induced to do so with the appropriate developmental signals the principal known source of stem cells in the adult are the mesenchymal stem cells or fibroblasts of the bone marrow shown to be capable of differentiating into cells of the skeletal system e g bone cartilage tendon endothelial cardiac and neural cells it is highly probable that specific signaling complexes e g those produced and used by the methods described in a concurrently filed application referred to herein are capable of inducing a much broader range of phenotypes in the fibroblast population found in the bone marrow and predictably from fibroblastic reservoirs which may come from other tissues e g lung connective and muscle tissue this discovery provides an opportunity to produce specific cells in large quantity for cell therapy and tissue engineering a property of the stem cells of the dermal tissue which distinguishes them is the induced expression of the stem cell marker cd34 expressed after the stem cells are cultured and passaged in dmem with an extract of mes mouse embryonic stem cells mes cells are spun into a pellet and resuspended in pbs and sonicated at 4 u00b0 c for between 5 and 10 seconds about 10 times with 10 0 second intervals the suspension is then.