Distribution of peripheral blood cells in mice after splenectomy or autotransplantation

Spleen regeneration after subcutaneous heterotopic autotransplantation in a mouse model

BACKGROUND

Splenectomy may lead to severe postoperative complications, including sepsis and cancers. A possible solution to this problem is heterotopic autotransplantation of the spleen. Splenic autografts rapidly restore the regular splenic microanatomy in model animals. However, the functional competence of such regenerated autografts in terms of lympho- and hematopoietic capacity remains uncertain. Therefore, this study aimed to monitor the dynamics of B and T lymphocyte populations, the monocyte-macrophage system, and megakaryocytopoiesis in murine splenic autografts.

METHODS

The model of subcutaneous splenic engraftment was implemented in C57Bl male mice. Cell sources of functional recovery were studied using heterotopic transplantations from B10-GFP donors to C57Bl recipients. The cellular composition dynamics were studied by immunohistochemistry and flow cytometry. Expression of regulatory genes at mRNA and protein levels was assessed by real-time PCR and Western blot, respectively.

RESULTS

Characteristic splenic architecture is restored within 30 days post-transplantation, consistent with other studies. The monocyte-macrophage system, megakaryocytes, and B lymphocytes show the highest rates, whereas the functional recovery of T cells takes longer. Cross-strain splenic engraftments using B10-GFP donors indicate the recipient-derived cell sources of the recovery. Transplantations of scaffolds populated with splenic stromal cells or without them afforded no restoration of the characteristic splenic architecture.

CONCLUSIONS

Allogeneic subcutaneous transplantation of splenic fragments in a mouse model leads to their structural recovery within 30 days, with full reconstitution of the monocyte-macrophage, megakaryocyte and B lymphocyte populations. The circulating hematopoietic cells provide the likely source for the cell composition recovery.

Spleen: Reparative Regeneration and Influence on Liver

This review considers experimental findings on splenic repair, obtained in two types of small animal (mouse, rat, and rabbit) models: splenic resections and autologous transplantations of splenic tissue. Resection experiments indicate that the spleen is able to regenerate, though not necessarily to the initial volume. The recovery lasts one month and preserves the architecture, albeit with an increase in the relative volume of lymphoid follicles. The renovated tissues, however, exhibit skewed functional profiles; notably, the decreased production of antibodies and the low cytotoxic activity of T cells, consistent with the decline of T-dependent zones and prolonged reduction in T cell numbers. Species-specific differences are evident as well, with the post-repair organ mass deficiency most pronounced in rabbit models. Autotransplantations of splenic material are of particular clinical interest, as the procedure can possibly mitigate the development of post-splenectomy syndrome. Under these conditions, regeneration lasts 1-2 months, depending on the species. The transplants effectively destroy senescent erythrocytes, assist in microbial clearance, and produce antibodies, thus averting sepsis and bacterial pneumonia. Meanwhile, cellular sources of splenic recovery in such models remain obscure, as well as the time required for T and B cell number reconstitution.

Haematological and biochemical characteristics of the splenic effluent blood in schistosomal patients undergoing splenectomy

OBJECTIVE

To assess hematological and biochemical features of splenic effluent blood and their influence on the rise of hematological values after splenectomy.

METHODS

we studied 20 patients undergoing surgical treatment for schistosomatic portal hypertension. We collected blood samples for CBC, coagulation, bilirubin and albumin in the splenic vein (perioperative) and peripheral blood (immediately pre and postoperative periods).

RESULTS

the splenic blood showed higher values of red blood cells, hemoglobin, hematocrit, platelet count, total leukocytes, neutrophils, lymphocytes, monocytes, eosinophils and basophils, as well as reduction of laboratory coagulation parameters in relation to peripheral blood collected preoperatively. In the postoperative peripheral blood there was an increase in the overall leukocytes and in their neutrophil component, and decreased levels of basophils, eosinophils and lymphocytes. The other postoperative variables of complete blood count and coagulation tests were not different compared with the splenic blood. The albumin values were lower postoperatively when compared to preoperative and splenic blood. There were higher values of direct bilirubin in the postoperative period when compared with the preoperative and splenic blood. Postoperative indirect bilirubin was lower compared to its value in the splenic blood.

CONCLUSION

hematological and biochemical values of splenic effluent blood are higher than those found in peripheral blood in the presence of schistosomal splenomegaly. However, the splenic blood effluent is not sufficient to raise the blood levels found after splenectomy.

Cholinergic neural signals to the spleen down-regulate leukocyte trafficking via CD11b

The cholinergic anti-inflammatory pathway is a physiological mechanism that inhibits cytokine production and diminishes tissue injury during inflammation. Recent studies demonstrate that cholinergic signaling reduces adhesion molecule expression and chemokine production by endothelial cells and suppresses leukocyte migration during inflammation. It is unclear how vagus nerve stimulation regulates leukocyte trafficking because the vagus nerve does not innervate endothelial cells. Using mouse models of leukocyte trafficking, we show that the spleen, which is a major point of control for cholinergic modulation of cytokine production, is essential for vagus nerve-mediated regulation of neutrophil activation and migration. Administration of nicotine, a pharmacologic agonist of the cholinergic anti-inflammatory pathway, significantly reduces levels of CD11b, a beta(2)-integrin involved in cell adhesion and leukocyte chemotaxis, on the surface of neutrophils in a dose-dependent manner and this function requires the spleen. Similarly, vagus nerve stimulation significantly attenuates neutrophil surface CD11b levels only in the presence of an intact and innervated spleen. Further mechanistic studies reveal that nicotine suppresses F-actin polymerization, the rate-limiting step for CD11b surface expression. These studies demonstrate that modulation of leukocyte trafficking via cholinergic signaling to the spleen is a specific, centralized neural pathway positioned to suppress the excessive accumulation of neutrophils at inflammatory sites. Activating this mechanism may have important therapeutic potential for preventing tissue injury during inflammation.

Staphylococcus aureus infection after splenectomy and splenic autotransplantation in BALB/c mice

Splenectomy results in an increased risk of sepsis. The autogenous transplant of the spleen is an option for preserving splenic functions after total splenectomy. In this study, the capacity of animals undergoing autogenous spleen transplantation to respond to Staphylococcus aureus infection was investigated. BALB/c mice were divided into three groups: splenectomy followed by autotransplantation in the retroperitonium (AT), splenectomized only (SP) and operated non-splenectomized sham control (CT). Thirty days after surgery the mice were infected intravenously with S. aureus. Splenectomized mice had a higher number of colony-forming units (CFU) of S. aureus in liver and lungs in comparison with either AT or with CT mice (P < 0.05). Higher CFU numbers in lung of SP mice correlated with elevated production of interleukin-10 associated with a lower production of interferon-gamma and tumour necrosis factor-alpha. However, systemically, the level of tumour necrosis factor-alpha was higher in the SP group than in CT or AT. Lower titres of specific anti-S. aureus immunoglobulin (Ig)M and IgG1 were observed 6 days after infection in SP mice in comparison either with the AT or CT groups. Thus, splenectomy is detrimental to the immune response of BALB/c mice against infection by S. aureus which can be re-established by autogenous implantation of the spleen.

Complications of splenectomy

Surgical removal of the spleen, splenectomy, is a procedure that has significantly decreased in frequency as our understanding of the infectious complications of the asplenic state increased. The full spectrum and details of splenic function, however, have yet to be fully outlined. As a result, our comprehension of the long-term consequences of splenectomy remains incomplete. We review the evidence relating to the effects of splenectomy on infection, malignancy, thrombosis, and transplantation. Perhaps the best-defined and most widely understood complication of splenectomy is the asplenic patient's susceptibility to infection. In response to this concern, novel techniques have emerged to attempt to preserve splenic function in those patients for whom surgical therapy of the spleen is necessary. The efficacy of these techniques in preserving splenic function and staving off the complications associated with splenectomy is also reviewed in this article.

Spleen autotransplantation. Morphological and functional follow-up after spleen autotransplantation in mice: A research summary

In 1986, we started the research on spleen surgery aimed at saving the splenic mass after its traumatic injury, with elaboration of special resection and autotransplantation techniques. The researches started on mongrel dogs and were continued on inbred mice and beagle dogs with complex histological, imaging, and laboratory investigations, following-up the function and the regeneration of autotransplanted spleen chips. Performing research on mice provided more immunological methods, such as lymphocyte subsets, immunoglobulin levels, and monitoring the phagocytic functions. Researches showed evidence also on the presence of apoptosis, furthermore, stem cell studies on regeneration and functional restoration of the spleen chips are in progress. Our results contributed to two multidisciplinary guidelines in Hungary: (1) One of them is under preparation and underlines the importance of spleen saving methods after traumatic splenic injury; (2) The second guideline shows that hemorheological changes can be early indicators of the increased sensitivity to postsplenectomy infections.

Cellular and serological changes in the peripheral blood of splenectomized and spleen autotransplanted mice

BACKGROUND

Our department worked out a modified surgical form of spleen autotransplantation earlier, named "spleen apron method" introduced already into the clinical practice. Recently we tested the immunological changes in a group of patients autotransplanted with about 10-15% of their spleen, what was the at least always implantable amount after the severe splenic injuries. In the current work we aimed at measuring some cellular and serological changes in the peripheral blood of splenectomized and spleen autotransplanted inbred mice two and eight months after the operations in order to get more unambiguous results than that we could obtain in our patients with this technique.

MATERIALS AND METHODS

We divided 96 two months old Balb/c female mice into eight groups (n = 12/group). The group of controls, sham operated, splenectomized and autotransplanted animals with two and eight months of survival time after the operations. During the autotransplantation we inserted the same amount of spleen, five slices, "chips," about 10-15% of total mass of spleen, into the greater omentum similarly as it was used in the patients. The concentration of serum proteins were measured by laser nephelometry. The lymphocyte subsets were analyzed by flow cytometry.

RESULTS

We found that two months after the operations the number of CD 19+ B-cells increased in the splenectomized but decreased in the autotransplanted animals. Eight months after the operations the number of both CD3+ T and CD19+ B lymphocytes decreased both in the splenectomized and autotransplanted animals compared to the controls and sham operated mice. However, the numbers of T and B cells were slightly but not significantly higher in the autotransplanted than in the splenectomized mice. The serum level of IgM was also decreased in the splenectomized and autotransplanted mice at both time points, however, eight months after the operations the concentration of IgM was significantly higher in the autotransplanted group than in the splenectomized animals.

CONCLUSION

The effects of autotransplanted "chips" were different at the various ages of the animals. Additionally, they showed some immunological benefit being quantitatively in accordance to the amount of the transplanted spleen. The elevated level of serum IgM what we found in the autotransplanted mice even with this amount of transplanted spleen eight months after the operations, however, might have the potentially greatest importance compared to splenectomy. These experiments can prove that the attempts for autotransplantation may have real perspectives but their efficacy depends on the amount of the successfully transplanted (saved) mass of spleen.