Hematopoietic stem cell (HSC) gene therapies hold immense potential for treating a growing list of genetic disorders, but the field has reached an inflection point where novel technologies are needed to overcome significant challenges, including high costs, unequal access, and prolonged disruption of daily life. Here, we describe a bedside cell manufacturing strategy in which HSCs are genetically targeted within gene therapy foam that is mixed with freshly isolated bone marrow aspirate concentrate and then directly injected back into the marrow. We demonstrate that highly efficient genetic reprogramming of CD34+ HSCs can be accomplished within methylcellulose-based foam, using low vector doses that are inefficient with conventional liquid-based approaches. In an ex vivo model of perfused bone marrow, we show that foam retains vector at the injection site and locally boosts gene transfer into embedded CD34+ progenitor cells while minimizing off-target events. We also establish that this foam technology is compatible with freshly harvested human bone marrow aspirate. Once implemented in the clinic, this new method, which can be performed in an outpatient setting of any regional hospital, could improve the effectiveness of stem cell-based gene therapies, while concomitantly lowering costs to make these treatments accessible to all who need them.
Keywords: HSC gene therapy; bedside manufacturing; bioengineering; foam; methylcellulose.
© 2025 The Authors.