Mice that have been reconstituted with geneX-transduced cells

Question

I read this article in the following:

... Mice that have been reconstituted with geneX-transduced cells

Now, someone who is not familiar with animal sciences, what does this exactly mean? It is in the context of hematopoietic stem cells. I have two possible interpretations as a result:

1. An Hematapoetic stem cell with geneX was successfully transplanted into the mouse
2. The mouse cells (from the embryo) were engineered to contain geneX, and hence the mouse has been reconstituted with geneX transduced cells

Are any of these correct? If I am wrong please let me know!

Answer 1

Your second interpretation is correct. The mice have been reconstituted from stem cells that were "transduced" (using a viral vector) with a construct containing the appropriate geneX. The link gives comparison of transduction vs. transfection.

https://www.vectalys.com/blog/what-are-the-differences-between-transfection-and-transduction-222