Does Period Blood Have Stem Cells? A Surprising Discovery

Menstrual blood has long been considered a biological waste product, but recent research suggests it holds unexpected medical potential. Scientists have discovered that menstrual fluid contains cells with regenerative properties, sparking interest in their possible applications in medicine and tissue engineering.

This discovery challenges previous assumptions about menstrual discharge and opens new avenues for scientific exploration.

Composition of Menstrual Discharge

Menstrual discharge is a complex biological fluid composed of more than just blood. It includes endometrial tissue, cervical mucus, vaginal secretions, and immune cells, making it distinct from venous blood. The endometrial lining, which sheds during menstruation, contains epithelial cells, stromal cells, and extracellular matrix proteins, contributing to the fluid’s texture and consistency.

Unlike blood from a wound, menstrual fluid has a lower concentration of clotting factors such as fibrinogen, which explains its typically more fluid consistency. The presence of anticoagulants like plasmin prevents excessive clot formation, allowing for a smoother expulsion of the uterine lining. Additionally, menstrual discharge contains proteins, enzymes, and signaling molecules that facilitate the breakdown and removal of endometrial tissue.

Hormonal fluctuations regulate menstrual fluid composition. As progesterone levels drop, the spiral arteries supplying the endometrium constrict, leading to tissue breakdown and cellular debris release. This process also introduces inflammatory mediators that support tissue remodeling and repair.

Presence of Progenitor Cells

Menstrual blood has drawn scientific interest due to the presence of progenitor cells with regenerative potential. These endometrial stem-like cells, known as menstrual-derived mesenchymal stromal cells (MenSCs), originate from the endometrial lining and share properties with mesenchymal stem cells (MSCs) found in bone marrow and adipose tissue. Unlike traditional MSCs, MenSCs are more accessible and can be collected non-invasively, making them a promising candidate for regenerative medicine.

Studies have shown that MenSCs can differentiate into various cell types, including osteogenic, chondrogenic, adipogenic, and neurogenic lineages. Research published in Stem Cell Research & Therapy found that MenSCs exhibit high proliferative capacity and express key stem cell markers such as CD90, CD105, and CD73 while lacking hematopoietic markers like CD34 and CD45. This profile aligns with mesenchymal stromal cell characteristics, reinforcing their therapeutic potential.

Beyond differentiation, MenSCs secrete bioactive molecules that promote tissue repair and immune modulation. Their secretome includes growth factors, cytokines, and extracellular vesicles that enhance angiogenesis, reduce fibrosis, and regulate inflammation. Research in Frontiers in Cell and Developmental Biology highlighted that MenSC-derived exosomes improve wound healing by stimulating fibroblast migration and collagen deposition, underscoring their regenerative capabilities. These properties have led to investigations into their use for treating ischemic stroke, myocardial infarction, and degenerative diseases.

Processes of Isolation and Identification

Collecting and processing menstrual-derived progenitor cells require precise methodologies to ensure viability and purity. Menstrual fluid is typically obtained using sterile menstrual cups or soft collection devices, which minimize contamination and preserve cellular integrity. Once collected, the sample undergoes immediate processing to prevent degradation. Centrifugation separates cellular components from plasma, isolating the stromal cell-rich fraction. Enzymatic digestion with collagenase or trypsin further breaks down endometrial tissue, releasing progenitor cells into suspension.

After isolation, these cells are cultured under controlled conditions to assess growth potential and stability. Standard culture media supplemented with fetal bovine serum or platelet lysate support expansion while maintaining stem-like properties. Researchers monitor cell morphology and adherence characteristics, as menstrual-derived stromal cells exhibit a fibroblast-like appearance similar to mesenchymal stem cells from other sources. Colony-forming unit assays quantify their proliferative capacity.

Flow cytometry confirms cell identity by analyzing surface marker expression. Menstrual-derived progenitor cells typically express mesenchymal markers such as CD73, CD90, and CD105 while lacking hematopoietic markers like CD34 and CD45. This immunophenotypic profile aligns with mesenchymal stromal cell criteria established by the International Society for Cell & Gene Therapy (ISCT). Differentiation assays further validate multipotency, with cells induced into osteogenic, adipogenic, or chondrogenic lineages and assessed for lineage-specific staining and gene expression.