A major finding of this study is the identification of a monocyte reservoir in the spleen, which can rapidly deploy monocytes to inflammatory sites. The spleen contains a large population of monocytes that are distinct from macrophages and dendritic cells. These monocytes can exit the spleen in response to tissue injury, such as myocardial infarction, and migrate to the injured tissue to participate in wound healing. The spleen acts as a storage site for monocytes, which can be mobilized quickly when needed. This discovery highlights the spleen's role in regulating inflammation by providing a ready supply of monocytes. Monocytes are typically considered to circulate in the blood and differentiate into macrophages or dendritic cells upon tissue entry. However, this study shows that a significant portion of monocytes reside in the spleen and are not immediately available in the blood. These splenic monocytes are similar to their blood counterparts in morphology and gene expression, and they can differentiate into macrophages or dendritic cells in vitro. The spleen's subcapsular red pulp contains clusters of these monocytes, which are distinct from macrophages and dendritic cells. In response to ischemic myocardial injury, splenic monocytes increase their motility, exit the spleen, and accumulate in the injured tissue. This process is facilitated by chemokine signaling, particularly through the CCR2 receptor. The study also shows that the spleen is a major source of monocytes that contribute to the inflammatory response in the heart. Splenic monocytes are mobilized in response to tissue injury and can be rapidly recruited to the site of inflammation. The study also demonstrates that the spleen can mobilize monocytes in response to surgical induction of ischemia. This process is dependent on the angiotensin II (Ang II)–AT-1 receptor signaling pathway. Ang II induces cytoskeletal rearrangement and migration of monocytes in vitro and in vivo, and it is involved in the recruitment of monocytes to the site of inflammation. The study further shows that the spleen can rapidly release monocytes in response to injury, which can then migrate to the injured tissue to participate in wound healing. The spleen's role as a monocyte reservoir is supported by the observation that splenic monocytes can be tracked in real-time using intravital microscopy. This technique allows for the observation of monocyte behavior in the spleen and their migration to the site of injury. The study also shows that the spleen is not the primary source of monocytes in the blood, but it can provide a significant number of monocytes when needed. Overall, this study highlights the spleen's role as a monocyte reservoir that can rapidly deploy monocytes to inflammatory sites. The spleen provides a ready supply of monocytes that can be mobilized quickly in response to tissue injury, which is essential for wound healing and the regulation of inflammation. The study also suggestsA major finding of this study is the identification of a monocyte reservoir in the spleen, which can rapidly deploy monocytes to inflammatory sites. The spleen contains a large population of monocytes that are distinct from macrophages and dendritic cells. These monocytes can exit the spleen in response to tissue injury, such as myocardial infarction, and migrate to the injured tissue to participate in wound healing. The spleen acts as a storage site for monocytes, which can be mobilized quickly when needed. This discovery highlights the spleen's role in regulating inflammation by providing a ready supply of monocytes. Monocytes are typically considered to circulate in the blood and differentiate into macrophages or dendritic cells upon tissue entry. However, this study shows that a significant portion of monocytes reside in the spleen and are not immediately available in the blood. These splenic monocytes are similar to their blood counterparts in morphology and gene expression, and they can differentiate into macrophages or dendritic cells in vitro. The spleen's subcapsular red pulp contains clusters of these monocytes, which are distinct from macrophages and dendritic cells. In response to ischemic myocardial injury, splenic monocytes increase their motility, exit the spleen, and accumulate in the injured tissue. This process is facilitated by chemokine signaling, particularly through the CCR2 receptor. The study also shows that the spleen is a major source of monocytes that contribute to the inflammatory response in the heart. Splenic monocytes are mobilized in response to tissue injury and can be rapidly recruited to the site of inflammation. The study also demonstrates that the spleen can mobilize monocytes in response to surgical induction of ischemia. This process is dependent on the angiotensin II (Ang II)–AT-1 receptor signaling pathway. Ang II induces cytoskeletal rearrangement and migration of monocytes in vitro and in vivo, and it is involved in the recruitment of monocytes to the site of inflammation. The study further shows that the spleen can rapidly release monocytes in response to injury, which can then migrate to the injured tissue to participate in wound healing. The spleen's role as a monocyte reservoir is supported by the observation that splenic monocytes can be tracked in real-time using intravital microscopy. This technique allows for the observation of monocyte behavior in the spleen and their migration to the site of injury. The study also shows that the spleen is not the primary source of monocytes in the blood, but it can provide a significant number of monocytes when needed. Overall, this study highlights the spleen's role as a monocyte reservoir that can rapidly deploy monocytes to inflammatory sites. The spleen provides a ready supply of monocytes that can be mobilized quickly in response to tissue injury, which is essential for wound healing and the regulation of inflammation. The study also suggests