Valproic acid-expanded cord blood CD34+CD90+ cells are functionally distinct based on their origin.

Area of Science:

• * Stem Cell Biology
• * Hematology
• * Pharmacology

Background:

• * Hematopoietic stem cell (HSC) transplantation is crucial for treating hematologic malignancies but faces donor shortages.
• * Umbilical cord blood (UCB) offers an alternative HSC source, yet limited cell numbers necessitate ex vivo expansion.
• * Valproic acid (VPA) was previously shown to maintain functional HSCs in culture but not expand them.

Purpose of the Study:

• * To determine the origin and functionality of CD34+CD90+ cells after ex vivo culture with VPA.
• * To differentiate between HSC expansion via replication versus reprogramming.

Main Methods:

• * Flow cytometry sorting of CD34+CD90- and CD34+CD90+ cells from VPA-treated cultures.
• * Colony-forming unit (CFU) assays to assess progenitor cell function.
• * Xeno-transplantation studies in mice to evaluate in vivo hematopoietic reconstitution.

Main Results:

• * VPA culture significantly increased CD34+CD90+ cell numbers, primarily from pre-existing CD34+CD90+ cells.
• * CD34+CD90+ cells derived from CD34+CD90- cells exhibited reduced CFU plating efficiency.
• * Xeno-transplantation revealed diminished hematopoietic reconstitution potential for CD34+CD90+ cells originating from CD34+CD90- cells.
• * These reprogrammed cells showed increased mitochondrial mass but reduced regenerative capacity.

Conclusions:

• * VPA promotes the expansion of CD34+CD90+ cells mainly through the proliferation of existing primitive cells.
• * HSCs derived from more mature CD34+CD90- cells via VPA treatment are functionally differentiated and possess reduced regenerative potential.
• * Functional assessment of expanded HSCs is critical for evaluating their therapeutic efficacy.