The bone marrow, as a crucial reservoir of stem cells, provides a conducive environment for the development of various cell types, with CD34+ cells playing a central role. The expression of the CD34 marker on these cells distinguishes them within this rich microenvironment, indicating significant potential in terms of tissue regeneration and cellular differentiation.    
CD34 is a glycosylated transmembrane protein and represents a well-established marker for human hematopoietic stem and progenitor cells in peripheral blood, bone marrow, and cord blood. CD34+ cells are self-renewing, multipotent stem cells that give rise to all blood cells of the immune system through a process called hematopoiesis. As hematopoietic stem cells progress through hematopoiesis they generate the myeloid (monocytes, macrophages, granulocytes, megakaryocytes, dendritic cells, erythrocytes) and lymphoid (T cells, B cells, NK cells) lineages. The highly specialized cells that arise from hematopoietic stem cells work collaboratively in defending the body against infection and disease.
Thus, the duality between CD34- and CD34+ cells in the bone marrow provides a valuable functional diversity, prompting in-depth research to better understand their unique properties. This profound understanding is essential to fully harness the regenerative and therapeutic potential of these cells in the context of regenerative medicine and innovative clinical applications.