Scoring of skin rejection in a swine composite tissue allograft model

Exploring Iodide and Hydrogen Sulfide as ROS Scavengers to Delay Acute Rejection in MHC-Defined Vascularized Composite Allografts

Vascularized composite allografts (VCA) face ischemic challenges due to their limited availability. Reperfusion following ischemia triggers oxidative stress and immune reactions, and scavenger molecules could mitigate ischemia-reperfusion injuries and, therefore, immune rejection. We compared two scavengers in a myocutaneous flap VCA model. In total, 18 myocutaneous flap transplants were performed in Major histocompatibility complex (MHC)-defined miniature swine. In the MATCH group (n = 9), donors and recipients had minor antigen mismatch, while the animals were fully mismatched in the MISMATCH group (n = 9). Grafts were pretreated with saline, sodium iodide (NaI), or hydrogen sulfide (H2S), stored at 4 °C for 3 h, and then transplanted. Flaps were monitored until clinical rejection without immunosuppression. In the MATCH group, flap survival did not significantly differ between the saline and hydrogen sulfide treatments (p = 0.483) but was reduced with the sodium iodide treatment (p = 0.007). In the MISMATCH group, survival was similar between the saline and hydrogen sulfide treatments (p = 0.483) but decreased with the sodium iodide treatment (p = 0.007). Rhabdomyolysis markers showed lower but non-significant levels in the experimental subgroups for both the MATCH and MISMATCH animals. This study provides insightful data for the field of antioxidant-based approaches in VCA and transplantation.

Immunohistochemical Analysis of Lymphocyte Populations in Acute Skin Rejection: The University Health Network Addition to the Banff Classification

Acute rejection in vascularized composite allotransplantation has been identified using the Banff 2007 working classification. We propose an addition to this classification based on histological and immunological assessment within the skin and subcutaneous tissue.

Methods

Biopsies from vascularized composite transplant patients were obtained at scheduled visits and whenever skin changes occurred. Histology and immunohistochemistry were performed on all samples, looking at infiltrating cells.

Results

Observations were made specifically related to each component of the skin, including the epidermis, dermis, vessels, and subcutaneous tissue. Our findings led to the establishment of the University Health Network addition of skin rejection.

Conclusions

The high rate of rejection where the skin is involved requires novel techniques for early detection. The University Health Network skin rejection addition can serve as an adjunct to the Banff classification.

Imaging human skin autograft integration with optical coherence tomography

Background

Skin autografting is a common clinical procedure for reconstructive surgery. Despite its widespread use, very few studies have been conducted to non-invasively evaluate and monitor the vascular and structural features of skin grafts. This study, therefore, aims to demonstrate the potential of optical coherence tomography (OCT) alongside OCT-based angiography (OCTA) to non-invasively image and monitor human skin graft health and integration over time.

Methods

An in-house-built clinical prototype OCT system was used to acquire OCT/OCTA images from patients who underwent split-thickness skin graft surgery following severe burn damage to the skin. The OCT imaging was carried out at multiple locations over multiple time points with a field of view of ~9 mm × 9 mm and a penetration depth of ~1.5 mm. In addition to obtaining high-resolution qualitative images, we also quantitatively measured and compared specific structural and vascular parameters, such as identifiable layer thickness and corresponding vascular area density and diameter.

Results

Two patients (patient #1 and #2) were enrolled for this preliminary study. Vascular and structural features were successfully imaged and measured in the graft tissue and integration layer immediately beneath at different time points. Revascularization, healing, and integration were monitored with patient-specific details. Results of the quantitative image analysis from patient #1 indicated that integration layer thickness 16-day post-surgery was significantly less (~50%) than that of 7-day post-surgery. Additionally, with patient #2, significant growth (~20%) was seen with the vascular area density of both the graft and corresponding integration layer beneath between 6 and 14 days post-surgery.

Conclusions

Our preliminary studies show that OCT/OCTA has clinical potential to image and measure numerous features of human skin graft health and integration in the days and weeks following split-thickness surgery. For the first time, we demonstrate the applicability of non-invasive imaging technology for novel clinical uses that could eventually aid in the betterment of surgical practices and clinical outcomes.

Skin Immunology and Rejection in VCA and Organ Transplantation

Purpose of Review

Skin provides a window into the health of an individual. Using transplanted skin as a monitor can provide a powerful tool for surveillance of rejection in a transplant. The purpose of this review is to provide relevant background to the role of skin in vascularized transplantation medicine.

Recent Findings

Discrete populations of T memory cells provide distributed immune protection in skin, and cycle between skin, lymph nodes, and blood. Skin-resident TREGcells proliferate in response to inflammation and contribute to long-term VCA survival in small animal models. Early clinical studies show sentinel flap rejection to correlate well with facial VCA skin rejection, and abdominal wall rejection demonstrates concordance with visceral rejection, but further studies are required.

Summary

This review focuses on the immunology of skin, skin rejection in vascularized composite allografts, and the recent advances in monitoring the health of transplanted tissues using distant “sentinel” flaps.

Transforming Growth Factor-β Partially Reversed the Immunosuppressive Effect of Mesenchymal Stem Cells in Mice

BACKGROUND

Mesenchymal stem cells (MSCs) possess powerful immunosuppression capacity. Transforming growth factor-β (TGF-β) is a well-known anti-inflammatory cytokine and plays an important role in various inflammatory processes. We hypothesized that TGF-β could synergize with MSCs in suppressing immune responses, and therefore established a mouse skin graft model to evaluate the effect of MSCs and MSCs combined with TGF-β on transplantation immunity in vivo.

METHODS

Balb/c and C57BL/6 mice were used to establish the skin graft model. The recipients were divided into 3 groups and received intravenous bone marrow mesenchymal stem cells (BMSCs), BMSCs pretreated with TGF-β, and 0.9% saline solution, respectively. Skin graft survival time, pathological detection, the ratio of CD4+CD25+Foxp3+Treg cell of spleens, and the level of IFN-γ, IL-2, IL-10, and TGF-β expression were tested.

RESULTS

The survival time of skin grafts were prolonged in both BMSC (12.5 ± 1.35 days) and BMSC-TGF-β (10.6 ± 1.90 days) recipients compared to the blank control recipients (8.0 ± 1.05 days). The ratio of CD4+CD25+Foxp3+Treg cell of spleens from BMSC and BMSC-TGF-β recipients was higher than that of the blank control, and the upregulated proliferation in the BMSC group occurred earlier and was prolonged compared to the BMSC-TGF-β group. The expression of IFN-γ and IL-2 was inhibited in both the BMSC and BMSC-TGF-β groups compared to the blank, while the expression of IL-10 and TGF-β was boosted. In contrast to the BMSC group, the BMSC-TGF-β group exhibited a weaker effect on the expression of cytokines.

CONCLUSION

TGF-β partially reversed the immunosuppressive effect of MSCs in vivo. This immunoregulatory feature may have potential applications for treating transplant rejection.

A structurally distinct TGF-β mimic from an intestinal helminth parasite potently induces regulatory T cells

Helminth parasites defy immune exclusion through sophisticated evasion mechanisms, including activation of host immunosuppressive regulatory T (Treg) cells. The mouse parasite Heligmosomoides polygyrus can expand the host Treg population by secreting products that activate TGF-β signalling, but the identity of the active molecule is unknown. Here we identify an H. polygyrus TGF-β mimic (Hp-TGM) that replicates the biological and functional properties of TGF-β, including binding to mammalian TGF-β receptors and inducing mouse and human Foxp3⁺ Treg cells. Hp-TGM has no homology with mammalian TGF-β or other members of the TGF-β family, but is a member of the complement control protein superfamily. Thus, our data indicate that through convergent evolution, the parasite has acquired a protein with cytokine-like function that is able to exploit an endogenous pathway of immunoregulation in the host.

Heligmosomoides polygyrus can activate mammalian TGF-β signalling pathways, but how it does so is not known. Here the authors identify and isolate a H. polygyrus TFG-β mimic that can bind both mammalian TGF-β receptor subunits, activate Smad signalling and generate inducible regulatory T cells.

Immunosuppression for in vivo research: state-of-the-art protocols and experimental approaches

Almost every experimental treatment strategy using non-autologous cell, tissue or organ transplantation is tested in small and large animal models before clinical translation. Because these strategies require immunosuppression in most cases, immunosuppressive protocols are a key element in transplantation experiments. However, standard immunosuppressive protocols are often applied without detailed knowledge regarding their efficacy within the particular experimental setting and in the chosen model species. Optimization of such protocols is pertinent to the translation of experimental results to human patients and thus warrants further investigation. This review summarizes current knowledge regarding immunosuppressive drug classes as well as their dosages and application regimens with consideration of species-specific drug metabolization and side effects. It also summarizes contemporary knowledge of novel immunomodulatory strategies, such as the use of mesenchymal stem cells or antibodies. Thus, this review is intended to serve as a state-of-the-art compendium for researchers to refine applied experimental immunosuppression and immunomodulation strategies to enhance the predictive value of preclinical transplantation studies.

Hypercapnic acidosis prolongs survival of skin allografts

BACKGROUND

Evidence reveals that hypercapnic acidosis (HCA) modulates immune responses. However, the effect of HCA on allogenic skin graft rejection is unknown. We examined whether HCA might improve skin graft survival in a mouse model of skin transplantation.

METHODS

A major histocompatibility-complex-incompatible BALB/c to C57BL/6 mouse skin transplantation model was used. Animals were divided into sham control, air, and HCA groups. Mice in the HCA group were exposed daily to 5% CO2 in air for 1 h. Skin grafts were harvested for histologic analyses. Nuclear factor (NF)-κB activation was determined in harvested draining lymph nodes. Spleen weights and serum levels of tumor necrosis factor-α and chemokine (C-X-C motif) ligand 2 were serially assessed after skin transplantation.

RESULTS

Skin allografts survived significantly longer in the HCA group of mice than those in the air group. Allografted mice in the air group underwent a 2.1-fold increase in spleen weight compared with a 1.1-fold increase in the mice with HCA on day 3. There were increased inflammatory cell infiltration, folliculitis, focal dermal-epidermal separation, and areas of epidermal necrosis in the air group that were reduced with HCA treatment. In the HCA group, CD8(+) T cell infiltration at day 7 decreased significantly but not CD4(+) T cell infiltration. In addition, HCA significantly suppressed serum tumor necrosis factor-α on days 1 and 3 and chemokine (C-X-C motif) ligand 2 on days 1 and 10. Furthermore, the HCA group had remarkably suppressed NF-κB activity in draining lymph nodes.

CONCLUSIONS

HCA significantly prolonged the survival of incompatible skin allografts in mice by reducing proinflammatory cytokine production, immune cell infiltration, and NF-κB activation.

A novel rat full-thickness hemi-abdominal wall/hindlimb osteomyocutaneous combined flap: influence of allograft mass and vascularized bone marrow content on vascularized composite allograft survival

Vascularized bone marrow transplantation (VBMT) appears to promote tolerance for vascularized composite allotransplantation (VCA). However, it is unclear whether VBMT is critical for tolerance induction and, if so, whether there is a finite amount of VCA that VBMT can support. We investigated this with a novel VCA combined flap model incorporating full-thickness hemiabdominal wall and hindlimb osteomyocutaneous (HAW/HLOMC) flaps. Effects of allograft mass (AM) and VBMT on VCA outcome were studied by comparing HAW/HLOMC VCAs with fully MHC-mismatched BN donors and Lewis recipients. Control groups did not receive treatments following transplantation. Treatment groups received a short course of cyclosporine A (CsA), antilymphocyte serum, and three doses of adipocyte-derived stem cells (POD 1, 8, and 15). The results showed that all flaps in control allogeneic groups rejected soon after VCAs. Treatment significantly prolonged allograft survival. Three of eight recipients in HLOMC treatment group had allografts survive long-term and developed donor-specific tolerance. Significantly higher peripheral chimerism was observed in HLOMC than other groups. It is concluded that the relative amount of AM to VBMT is a critical factor influencing long-term allograft survival. Accordingly, VBMT content compared with VCA mass may be an important consideration for VCA in humans.

Preconditioned hyperbaric oxygenation protects skin flap grafts in rats against ischemia/reperfusion injury

Hyperbaric oxygen (HBO) therapy is an effective therapy for ischemia/reperfusion (I/R) injury of the brain, small intestine, testes and liver. However, the detailed molecular mechanisms underlying the effect of HBO therapy remain undetermined. In the current study, the hypothesis that preconditioning rats with HBO protects grafted skin flaps against subsequent I/R injury was investigated. In addition, the molecular mechanisms underlying HBO therapy were characterized by analyzing the roles of the following important inflammatory factors: High mobility group protein 1 (HMGB1) and nuclear factor-κ B (NF-κB). A total of 40 rats were randomly divided into the following five groups: (i) Sham surgery (SH); (ii) ischemia followed by reperfusion 3 days following surgery (I/R3d); (iii) ischemia followed by reperfusion 5 days following surgery (I/R5d); (iv) HBO preconditioning (HBO-PC) and ischemia followed by reperfusion 3 days following surgery (HBO-PC+3d); and (v) HBO-PC and ischemia followed by reperfusion 5 days following surgery (HBO-PC+5d). For the surgical procedure, all pedicled skin flaps were first measured and elevated (9×6 cm). The feeding vessels of the skin flaps were subsequently clamped for 3 h and released to restore blood flow. The rats in the HBO-PC+3d and HBO-PC+5d groups received 1 h HBO for 3 and 5 consecutive days, respectively, prior to surgery. Following surgery, the rats were euthanized, and grafted tissues were collected for western blotting and immunohistochemistry. HBO-PC increased blood perfusion in epigastric skin flaps and attenuated I/R injury following skin flap graft. Additionally, the elevated expression of HMGB1 and NF-κB proteins during I/R injury was attenuated by HBO-PC treatment. HBO-PC may therefore be applied to reduce I/R injury and improve the survival rate of grafted skin flaps. The molecular mechanisms underlying the effect of HBO therapy are associated with the attenuation of inflammatory responses.

Syngeneic adipose-derived stem cells with short-term immunosuppression induce vascularized composite allotransplantation tolerance in rats

BACKGROUND AIMS

A clinically applicable tolerance induction regimen that removes the requirement for lifelong immunosuppression would benefit recipients of vascularized composite allotransplantation (VCA). We characterized the immunomodulatory properties of syngeneic (derived from the recipient strain) adipocyte-derived stem cells (ADSCs) and investigated their potential to induce VCA tolerance in rats.

METHODS

ADSCs were isolated from Lewis (LEW, RT1A(l)) rats; their immunomodulatory properties were evaluated by means of mixed lymphocyte reactions in vitro and VCAs in vivo across a full major histocompatibility complex mismatch with the use of Brown-Norway (BN, RT1A(n)) donor rats. Two control and four experimental groups were designed to evaluate treatment effects of ADSCs and transient immunosuppressants (anti-lymphocyte globulin, cyclosporine) with or without low-dose (200 cGy) total body irradiation. Flow cytometry was performed to quantify levels of circulating CD4(+)CD25(+)FoxP3(+) regulatory T cells (Tregs).

RESULTS

Cultured syngeneic ADSCs exhibited CD90.1(+)CD29(+)CD73(+)CD45(-)CD79a(-)CD11b/c(-) phenotype and the plasticity to differentiate to adipocytes and osteocytes. ADSCs dramatically suppressed proliferation of LEW splenocytes against BN antigen and mitogen, respectively, in a dose-dependent fashion, culminating in abrogation of allo- and mitogen-stimulated proliferation at the highest concentration tested. Accordingly, one infusion of syngeneic ADSCs markedly prolonged VCA survival in LEW recipients treated with transient immunosuppression; of these, 66% developed tolerance. Total body irradiation provided no additional VCA survival benefit. An important role for Tregs in tolerance induction/maintenance was suggested in vivo and in vitro.

CONCLUSIONS

Treatment comprising syngeneic ADSCs and transient immunosuppression (i) increased levels of circulating Tregs and (ii) induced tolerance in 66% of recipients of major histocompatibility complex-mismatched VCAs.

Bone flap perfusion assessment using near-infrared fluorescence imaging

BACKGROUND

Microsurgical vascularized bone flaps are a versatile technique for reconstructing large bone defects. However, the assessment of perfusion is challenging, because clinical examination is difficult intraoperatively and often not possible postoperatively. Therefore, it is important to develop techniques to assess the perfusion of vascularized bone flaps and potentially improve the surgical outcomes. Near-infrared (NIR) fluorescence imaging has previously been shown to provide real-time, intraoperative evaluation of vascular perfusion. The present pilot study investigated the ability of NIR imaging to assess the perfusion of vascularized bone flaps.

METHODS

Vascularized bone flaps were created in female Yorkshire pigs using well-established models for porcine forelimb osteomyocutaneous flap allotransplantation (n = 8) and hindlimb fibula flaps (n = 8). Imaging of the bone flaps was performed during harvest using the FLARE intraoperative fluorescence imaging system after systemic injection of indocyanine green. Perfusion was also assessed using the standard of care by clinical observation and Doppler ultrasonography. NIR fluorescence perfusion assessment was confirmed by intermittent clamping of the vascular pedicle.

RESULTS

NIR fluorescence imaging could identify bone perfusion at the cut end of the osteotomy site. When the vascular pedicle was clamped or ligated, NIR imaging demonstrated no fluorescence when injected with indocyanine green. With clamp removal, the osteotomy site emitted fluorescence, indicating bone perfusion. The results using fluorescence imaging showed 100% agreement with the clinical observation and Doppler findings.

CONCLUSIONS

Vascularized bone transfers have become an important tool in reconstructive surgery; however, no established techniques are available to adequately assess perfusion. The results of our pilot study have indicated that NIR imaging can provide real-time, intraoperative assessment of bone perfusion.

Antigen-specific T-regulatory cells can extend skin graft survival time in mice

This study investigated the effects of donor antigen-specific CD4(+)CD25(+) T-regulatory cells (Tregs) on skin allografts in mice. An allogeneic skin transplant model was established using donor C57BL/6 or DBA and recipient BALB/c mice. Recipients were divided into 4 groups: control group without intervention (CON; C57BL/6 to BALB/c), rapamycin gavage group (RAP; C57BL/6 to BALB/c), CD4(+)CD25(+) Tregs-treated group (TRE; C57BL/6 to BALB/c), in which recipients received transfusions of CD4(+)CD25(+) Tregs stimulated with C57BL/6-derived immature dendritic cells, and the third-party donor group (DBA; DBA to BALB/c) in which recipients received transfusions of BALB/c CD4(+)CD25(+) Tregs stimulated with C57BL/6-derived immature dendritic cells. Mean (SD) survival time of the skin allografts in the TRE group was 17.0 (3.4) days, significantly longer than in the other groups: CON, 6.9 (1.9) days; RAP, 10.3 (3.0) days; and DBA, 10.8 (3.6) days. The TRE group demonstrated a significantly greater expression of transforming growth factor-β and interleukin (IL)-10. Donor antigen-specific CD4(+)CD25(+) Tregs effectively extend skin allograft survival in mice.

Prolongation of composite tissue allotransplant survival by treatment with bone marrow mesenchymal stem cells is correlated with T-cell regulation in a swine hind-limb model

BACKGROUND

Recently published reports indicate that treatment with mesenchymal stem cells combined with bone marrow transplantation could prolong survival after composite tissue allotransplantation. This study investigated whether bone marrow mesenchymal stem cells combined with irradiation and short-term immunosuppressant therapy, but without bone marrow transplantation, could prolong composite tissue allotransplantation survival. Correlation with regulatory T-cell populations was also evaluated in a swine hind-limb model.

METHODS

Heterotopic hind-limb transplantation was performed in outbred miniature swine. Group I (n = 4) was the untreated control. Group II (n = 3) received mesenchymal stem cells alone (on days -1, 3, 7, 14, and 21). Group III (n = 5) received cyclosporine A (on days 0 through 28). Group IV (n = 3) received irradiation (on day -1), mesenchymal stem cells (on days 1, 7, 14, and 21), and cyclosporine A (on days 0 to 28). Swine viability and signs of allograft rejection were monitored postoperatively. Histopathologic changes in allografts were examined. The expression and localization of CD4+/CD25+ and CD4+/FoxP3+ T cells were assessed using flow cytometry and immunohistochemistry.

RESULTS

Treatment with mesenchymal stem cells along with irradiation and cyclosporine A resulted in significant increases in allograft survival as compared with other groups (>120 days; p = 0.018). Histologic examination revealed the lowest degree of rejection in grafted skin and interstitial muscle layers in the mesenchymal stem cell/irradiation/cyclosporine A group. Flow cytometric analysis revealed a significant increase in the percentage of CD4+/CD25+ and CD4+/FoxP3+ T cells in both the blood and graft in the mesenchymal stem cell/irradiation/cyclosporine A group.

CONCLUSION

These results suggest that prolonged survival after composite tissue allotransplantation induced by treatment with mesenchymal stem cells combined with irradiation/cyclosporine A is correlated with regulatory T cells.

Prolonged cold ischemic time results in increased acute rejection in a rat allotransplantation model

BACKGROUND

The cold ischemic time may be more prolonged for facial tissue allografts than for organ allografts. Previous researches have shown that prolonged ischemia resulted in increased signs of rejection in a rat groin allotransplantation model; however, the relationship between cold ischemia and alloantigen-induced rejection was unclear.

MATERIALS AND METHODS

Vascularized groin flaps were transplanted from BN to Lewis rats after 0, 6, 12, 18, or 24 h of storage at 4 °C, and the allografts in each group were evaluated daily. Biopsy samples taken from the allo-0 h and allo-24 h groups on postoperative d 2-8 were graded for signs of acute rejection. Biopsy samples taken from the allo-0 h and allo-24 h groups on postoperative d 5 were stained for chemokine receptor CXCR3.

RESULTS

When the cold ischemia time was greater than 18 h, the survival time of the grafts was significantly shorter (6.2 ± 1.3 d) than that of the grafts that did not undergo cold ischemia (9.0 ± 1.2 d). Histological valuation showed acceleration of activated lymphocyte infiltration in the allo-24 h group (2.2 ± 0.4 d) compared with the allo-0 h group (4.8 ± 0.4 d). Furthermore, the proportion of CXCR3-positive cells in the allo-24 h group (49.7% ± 6.0%) was significantly higher than that in the allo-0 h group (22.9% ± 3.4%) on d 5 after transplantation.

CONCLUSIONS

Prolonged ischemia has a deleterious effect on allograft survival, and the chemokine receptor CXCR3 may play a role in this process.

A tolerogenic semimature dendritic cells induce effector T-cell hyporesponsiveness by activation of antigen-specific CD4+CD25+ T regulatory cells that promotes skin allograft survival in mice

Semimature dendritic cells (smDCs) can induce autoimmune tolerance by activation of host antigen-specific CD4(+)CD25(+) regulatory T (Treg) cells. We hypothesized that donor smDCs injected into recipients would induce effector T-cell hyporesponsiveness by activating CD4(+)CD25(+)Treg cells, and promote skin allograft survival. Myeloid smDCs were derived from C57BL/6J mice (donors) in vitro. BALB/c mice (recipients) were injected with smDCs to generate antigen-specific CD4(+)CD25(+)Treg cells in vivo. Allograft survival was prolonged when BALB/c recipients received either C57BL/6J smDCs prior to grafting or C57BL/6J smDC-derived CD4(+)CD25(+)Treg cells post-grafting, and skin flaps from these grafts showed the highest IL-10 production regardless of rapamycin treatments. Our findings confirm that smDCs constitute an independent subgroup of DCs that play a key role for inducing CD4(+)CD25(+)Treg cells to express high IL-10 levels, which induce hyporesponsiveness of effector T cells. Pre-treating recipients with donor smDCs may have potential for transplant tolerance induction.

Mesenchymal stem cells prolong composite tissue allotransplant survival in a swine model

BACKGROUND

This study investigated whether mesenchymal stem cells (MSCs) combined with bone marrow transplantation (BMT), irradiation, or short-term immunosuppressant therapy could prolong composite tissue allotransplant survival in a swine hind-limb model.

METHODS

Heterotopic hind-limb transplantation was performed in outbred miniature swine. Group I (n=5) was the untreated control. Group II (n=3) received MSCs alone (given on days -1, +3, +7, +14, +21). Group III (n=6) received cyclosporine A (CsA days 0 to +28). Group IV (n=4) received preconditioning irradiation (day -1), BMT (day +1), and CsA (days 0 to +28). Group V (n=5) received irradiation (day -1), BMT (day +1), CsA (days 0 to +28), and MSCs (days +1, +7,+14). The expression and localization of CD4/CD25 T cells and MSCs were assessed using flow cytometry and immunohistochemistry.

RESULTS

The allografts survival with MSCs alone revealed a significant prolongation, when compared with the controls (P=0.02). Allografts with CsA treatment exhibited delayed rejection. Irradiation and BMT-CsA treatment revealed no significant allograft survival benefit when compared with the CsA treatment group, but graft-versus-host disease (GVHD) was evident. However, combination of MSCs-BMT-CsA treatment demonstrated significant prolongation of allograft survival (>200 days, P<0.001) and no signs of GVHD with the lowest degree of rejection in the allo-skin and interstitial muscle layers. The CD4/CD25 regulatory-like T-cell expression in the circulating blood and allo-skin significantly increased in the MSC-BMT-CsA group. Examination of bromodeoxyuridine-labeled MSCs revealed donor MSC engraftment into the recipient and donor skin and the recipient liver parenchymal tissue.

CONCLUSION

These results suggested that the regulatory activity of MSCs on T cells and GVHD might contribute to significant prolongation of composite tissue allotransplant survival in the MSC-BMT-CsA treatment.

Outcomes of the first 2 American hand transplants at 8 and 6 years posttransplant

PURPOSE

The feasibility of hand allotransplantation has been demonstrated. The purpose of the article is to report the (1) functional return, (2) psychosocial outcomes, (3) clinical and histological assessment for rejection, (4) complications, and (5) graft survival in the 2 American hand transplant recipients.

METHODS

We present 2 patients 106 and 81 months, respectively, after unilateral transplantation of an allogeneic hand and forearm. We analyzed clinical course, number of rejection episodes, adverse events, function of the allograft, and quality of life. Clinical laboratory results, biopsy histology, and patient clinical examinations were used to compare the clinical course. Standard hand function tests were used to evaluate function. Psychological interviews were used to assess acceptance and quality of life.

RESULTS

Our patients have allograft survival with improvements in intrinsic muscle activity, total active motion and return of functional grip, pinch strength, and sensibility. Rejection episodes were restricted primarily to the first 6 months after transplantation, and all responded to treatment. The major posttransplantation complications were a cytomegalovirus infection in patient 1 and osteonecrosis of the hip requiring both hips to be replaced, 1 at year 4 and the other at year 6, as well as transient immunosuppression-related diabetes in patient 2. Recently we have weaned both patients off maintenance steroids. Current Carroll scores are fair for patient 1 (72/99) and fair for patient 2 (55/99), although patient 2 has not had good recovery of intrinsic function. Both patients are back at work and report an excellent quality of life at nearly 9 and 7 years, respectively, after transplantation.

CONCLUSIONS

Our intermediate long-term results of hand transplants have demonstrated functional return similar to that of replants. Graft survival and quality of life after hand transplantation has far exceeded initial expectations. We conclude that allogeneic hand transplant is feasible and holds promise as a treatment modality for catastrophic upper extremity loss.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

A modified model of hindlimb osteomyocutaneous flap for the study of tolerance to composite tissue allografts

Composite tissue allotransplantation (CTA) is the new frontier in transplantation. More than 25 hand allograft transplants have been performed worldwide, and the feasibility has been well established. The classical experimental model of CTA involves rat orthotopic hindlimb transplantation, a time-consuming procedure associated with high mortality and morbidity. We describe a rat heterotopic osteomyocutaneous flap that serves as a nonfunctional CTA, allowing the study of tolerance induction to a highly antigenic vascularized allograft of bone, muscle, and skin while minimizing the morbidity and mortality of full hind limb transplantation. In the present studies, we explored whether establishing chimerism by nonmyeloablative conditioning would induce tolerance to CTA. When compared with the classic hind limb transplantation model, these results demonstrate that our heterotopic hind limb flap is less morbid and as an effective experimental model for the study of CTA tolerance.

The immunology of composite tissue transplantation

Composite tissue allotransplantation holds great potential for reconstructive surgery. That these procedures can be successful has been clearly demonstrated by the success of hand, face, and larynx transplants around the world. Although the immunology of composite tissue allotransplantation mirrors that of any allogeneic organ transplant, there are several unique aspects to these grafts. This article reviews the immunology of transplantation, histocompatibility testing for composite tissue allotransplantation, graft rejection, immunosuppression, and specific immunologic considerations of composite tissue allotransplantation.

[Experimental and clinical experience of composite tissues allotransplantation in reconstructive surgery]

Composite tissue allotransplantation (CTA) is a new concept in reconstructive surgery to improve major physical defects with no current solution. Although not a life-saving procedure, tissue replacement by CTA offers great potential for improving quality of life but relies on lifelong immunotherapy. This new practice has become achievable with the refinement of microsurgical techniques, with experience gained from limb and scalp replantations, with the development of organ transplantation and the release of new immunosuppressive drugs. Experimental and clinical research made it possible. The first human cases of CTA proved the reality and the feasibility of the concept. While the early functional results of these allografts are encouraging, they will need to be assessed in the long-term, and development of less toxic - more efficient immonu-suppressive drugs will be a permanent requisite to the broadening of CTA. Although long-term outcome and potential adverse effects of chronic immunosuppression remain uncertain, as for organ transplantation, CTA is already a potential solution for some highly selected patients carrying physical disabilities such as large facial defects and bilateral hand amputation.

Induction of heat shock proteins in a rat composite tissue allotransplantation model of acute rejection

BACKGROUND

Clinical cases of composite tissue allotransplantation have been reported, but the exact mechanisms of allograft rejection remain unclear. The current study examined the possible involvement of heat shock proteins in major histocompatibility complex-compatible minor-mismatch composite tissue allotransplantation rejection.

METHODS

Allotransplantation (Fisher 344 to Lewis) and isotransplantation (Lewis to Lewis) of rat lower extremities were performed. Temporal profiles of 70-kDa and 60-kDa heat shock proteins (heat shock protein 70 and heat shock protein 60) were conducted by quantitative Western blot analysis and immunohistochemistry. Analyses were performed immediately after reperfusion (day 0) and on postoperative days 1, 3, 7, and 12 (n = 5 for quantitative Western blot analysis and n = 5 for immunohistochemistry).

RESULTS

The expression levels of the inducible forms of heat shock protein 70 and heat shock protein 60 were uniformly and significantly augmented until postoperative day 7 in the allografts, compared with the isografts (p < 0.001 for each protein). Immunoreactivities to heat shock protein 70 and heat shock protein 60 in keratinocytes, hair follicular cells, and endothelial cells of the subdermal vascular plexus were enhanced in the allografts early on postoperative day 1. Positive staining of hair follicles extended to deeper parts of the hair follicles and hair bulbs in the allografts on postoperative day 3. Although dendritic cells were positive for both heat shock protein 70 and heat shock protein 60, infiltrating lymphocytes were positive only for heat shock protein 60.

CONCLUSIONS

These results suggest the possible involvement of heat shock proteins in the process of major histocompatibility complex-compatible minor-mismatch composite tissue allotransplantation rejection. Thus, modulation of the function of heat shock proteins might be an important therapeutic option for improving the outcome of minor-mismatch allografts.

Composite Tissue Allotransplantation: Classification of Clinical Acute Skin Rejection

BACKGROUND

Composite tissue allotransplantation (CTA) is a recently introduced option for limb replacement and reconstruction of other nonreconstructible tissue defects. As with recipients of other allotransplants, CTA recipients can experience rejection episodes that are presumed to be mediated by immune mechanisms similar to those affecting solid organ grafts. However, a systematic examination of this process has not been performed, and there are no standardized criteria for the description of severity or type of rejection.

METHODS

We collected biopsies from human limb allografts and abdominal walls in various stages of rejection for histological and immunohistochemical analysis to formulate a CTA rejection scheme. Biopsies were ranked by severity and reproducibility of the system was tested using a second set of biopsies. Tissue slides were examined blindly by three pathologists and the nonparametric Kendall coefficient of concordance (W) was used to assess the amount of agreement among the pathologists in their classification grades.

RESULTS

Rejection initially appeared as a perivascular infiltrate progressing to involve the dermis. Arteritis was observed only in the medium to large size arteries of the subcutis. Myositis was seen occasionally. Perineural involvement without frank neuritis was present in advanced rejection. The infiltrate was predominantly CD4+ in milder cases and CD8+ in advanced cases. HLA-DR was minimally expressed in keratinocytes even in severe rejection. Kendall's W was 0.9375 (p< or =0.0001).

CONCLUSIONS

Based on this survey, we proposed an initial classification system for acute rejection in the skin of a CTA and demonstrated that this system is easily reproduced by independent pathologists.

Donor Leukocytes Combined With Delayed Immunosupressive Drug Therapy Prolong Limb Allograft Survival

Donor leukocytes administered at the time of transplantation may prolong organ allograft survival. Delayed administration of calcineurin inhibitors, such as FK506 or cyclosporine, may enhance their efficacy. Herein the effectiveness of this strategy to promote limb transplant survival was investigated in the strong histocompatibility barrier of Brown-Norway donor to Lewis recipients. Donor leukocytes (6 x 10(7) intravenously) were injected on the day of transplantation followed on day 1 to 14 with mycophenolate mofetil (MMF; 15 mg/kg/d) and prednisone, (0.5 mg/kg/d) which were then tapered by 20% each week and stopped at week 7. Administration of of FK506 (2 mg/kg/d) was started on day 4 and continued for 8 weeks, then tapered for 4 weeks to a maintenance dose of 0.8 mg/kg/d, which was continued for 12 weeks (group A; n = 8). A control group (n = 8) underwent identical treatment save for donor leukocyte injection but rather commencement of FK506 on day 1. Rejection was common during FK506 tapering in both groups. However group A showed a significantly later onset, a shorter period for reversal of the first rejection, and a significantly lower dosage of FK506 at the time of rejection. After the completion of immunosuppression, rejection occurred significantly later in group A than the control group with one animal surviving without immunosuppression on day 344. This is the first trial of a donor leukocyte injection combined with delayed FK506 administration in limb transplantation, which suggested that it could produce a modest but significant improvement in outcome.

Bone quality and healing in a swine vascularized bone allotransplantation model using cyclosporine-based immunosuppression therapy

Although vascularized bone and joint allotransplantation is a promising new treatment option for reconstructing large bone defects, the need for immunosuppressive agents to prevent rejection in these procedures poses a major problem. This problem stems from the fact that several of these agents can cause harmful side effects, such as alterations in bone quality and healing. Therefore, the purpose of this study was to determine what effect the commonly used immunosuppressant regimen cyclosporine A-based combination therapy has on bone quality and healing. In 10 pigs, vascularized bone allografts with skin and muscle components (osteomyocutaneous free flaps) were transplanted from size-matched donor animals. Recipient animals received oral cyclosporine A/mycophenolate mofetil/prednisone therapy for 90 days. Bone quality was studied before and after transplantation by measuring the bone's acoustic velocity and density and calculating the bone's elastic coefficient. Bone healing was assessed using radiographic analysis. Four animals were lost as a result of graft rejection or immunosuppression-related complications before the 90-day endpoint of the study. Although bone specimens taken from the six animals that completed the 90-day protocol had histological signs of rejection, they all seemed to have normal bone healing. Posttransplant bone density values were significantly decreased (p < 0.05) (1544.7 +/- 47.5 kg/m3) as compared with pretransplant values (1722.7 +/- 44.1 kg/m3). Results of the acoustic velocity and elastic coefficients measurements showed a significant decrease (p < 0.05) in posttransplant values (from 3503.0 +/- 165.1 meters/sec to 2963.0 +/- 54.6 meters/sec and from 21.6 +/- 2.2 GPa to 13.6 +/- 0.5 GPa, respectively), indicating diminished bone quality. The findings indicate that cyclosporine A/mycophenolate mofetil/prednisone combination therapy is ineffective in preventing bone rejection, that it decreases bone quality, and that it is associated with systemic toxicity, suggesting that this immunosuppressive regimen at the doses used in this study is not ideal for vascularized bone allotransplantation procedures.

Bone Quality in Swine Composite Tissue Allografts: Effects of Combination Immunotherapy

BACKGROUND

Tacrolimus (FK506)/mycophenolate mofetil (MMF)/prednisone combination immunosuppression therapy has been found to effectively prevent composite tissue allograft (CTA) rejection with minimal toxicity in a preclinical porcine model. These findings have been reproduced in 24 human hands transplanted in 18 patients. In CTAs containing bone, adequate bone quality and healing are essential for long-term functional success. The purpose of this study was to determine the effect FK506/MMF/prednisone immunotherapy has on bone quality and healing.

METHODS

Forelimb CTA-flaps were transplanted in nine pigs. Recipient animals received FK506/MMF/prednisone therapy for 3 months. Bone quality was studied pre- and posttransplant by measuring acoustic velocity and density and by calculating elastic coefficients. Additional bone quality analyses were performed on unoperated limbs, and in bone grafts from two pigs that had autograft procedures performed. Bone healing was assessed using radiographic analysis.

RESULTS

Three animals were lost to immunosuppression-related complications before the endpoint of the study. The bone component of all six CTA-flaps showed normal healing. Although results of the bone density measurements were not significantly different when comparing pre- to posttransplant values, acoustic velocity and elastic coefficient measurements showed a significant decrease posttransplant indicating a decrease in bone quality.

CONCLUSIONS

FK506/MMF/prednisone combination therapy prevented rejection, did not adversely affect bone quality, and showed normal bone healing. The transplant procedure itself decreased bone quality more than the immunosuppression regimen did over the observation period in this study. Based on these findings, we conclude to prevent CTA failure it is important to monitor bone quality posttransplant.

Donor leukocytes combine with immunosuppressive drug therapy to prolong limb allograft survival

Donor leukocytes administered at the time of transplantation may prolong organ allograft survival. This study examined the effectiveness of donor leukocyte injection combined with immunosuppression for limb transplantation across the strong histocompatibility barrier of a Brown Norway donor to a Lewis recipient. Eight animals received 6 x 10(7) donor leukocytes injected on the day of transplantation. From day 1, FK506 (2 mg/kg/d), mycophenolate mofetil (MMF) (15 mg/kg/d), and prednisone (0.5 mg/kg/d) were administered for 2 weeks. After week 2, prednisone and MMF were both tapered by 20% of the initial dosage per week. After week 7, the animals received only FK506 (2 mg/kg/d). From week 8, FK506 was tapered to the maintenance dose of 0.8 mg/kg/d at week 10 and was stopped on week 24. A control group of 8 animals underwent identical treatment except that the leukocyte injection was omitted. Rejection was observed in both groups during FK506 monotherapy; however, the onset of early rejection episodes was significantly later, the period for reversal of the first rejection was significantly shorter, and the dosage of FK506 at the time of rejection was significantly lower among leukocyte-treated recipients. After completion of immunosuppression, survival was modestly prolonged in the leukocyte-treated group. One animal is surviving without immunosuppression on day 234. This trial of donor leukocyte injection combined with immunosuppression in limb transplantation showed a modest, but significant, improvement in outcome.

Targeted gene disruption of the heat shock protein 72 gene (hsp70.1) in the donor tissue is associated with a prolonged rejection-free survival in the murine skin allograft model

It is known that the expression level of the heat shock protein (HSP) is elevated in allograft tissues, but the specific role of the HSP in the acute rejection has not been elucidated. This study aims to determine how and when the HSP72 molecule works immunologically in the process of acute allograft rejection from a skin graft model in which HSP72 (hsp70.1 gene) knock out (KO) mice were adopted either as a donor or as a recipient. In experiment I, tail skin was grafted from either the HSP72 KO C57BL/6 mice or wild-type C57BL/6 mice--as the allograft control--onto the trunk of B10BR mice. The grafts were observed for any signs of rejection until the 14th day after the graft. The survival of the grafted skin from the two donor groups was analyzed by a log-rank method. The grafted skin was observed for the degree of rejection using light microscopy. In addition, the degree of apoptosis was assessed using a terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). A mixed lymphocyte reaction (MLR) was observed with HSP72 KO C57BL/6 splenocytes as the stimulator and B10BR mice lymphocytes as the responder cells. The cytokine levels, such as interleukin-2 (IL-2) and interferon-gamma, were measured from an MLR supernatant using enzyme-linked immunosorbent assay (ELISA). In experiment II, the tail skin was grafted in the opposite direction from the B10BR mice to the HSP72 KO or wild-type C57BL/6 mice, and the grafts were observed for any signs of rejection, as defined in experiment I. The absence of HSP72 expression was observed in the HSP72 KO mice lymphocytes after heat stress (42 degrees C) using Western blot analysis. In experiment I, the survival of the skin grafts from the HSP72 KO C57BL/6 mice was 12+/-1.3 days (median+/-S.E.), which was significantly longer than that from the allograft control donor (9+/-0.6 days; p=0.03). This coincided with the microscopic finding of the graft tissues. The MLR response of the CD4+ lymphocytes stimulated by HSP72 KO C57BL/6 splenocytes was lower, and the interferon-gamma concentration from the MLR supernatant was also lower. On Day 9, 3.7+/-1.1(mean+/-S.D.) TUNEL-positive cells per unit high-power field (HPF) were observed from the HSP72 KO C57BL/6 skin, which was significantly lower than that from the control skin (8.7+/-2.1 cells/HPF; p=0.045). In contrast, in experiment II, there was no difference in the survival of the skin graft either from the B10BR to HSP72 KO C57BL/6 mice or from the B10BR to the wild-type C57BL/6 mice. In summary, the survival of the skin grafts from the HSP72 KO C57BL/6 mice was prolonged, and the degree of rejection was lower than that from the allograft control. This means that the presence of HSP72 in the donor tissue is related to the up-regulation of acute rejection from the recipient immune system. The HSP72 KO mice as the donor were shown to have decreased level of antigen presentation to the recipient CD4+ lymphocytes. Therefore, the HSP72 molecule from the donor cells is believed to be related to the induction of the recipient immune reaction via alloantigen presentation.

Experimental limb transplantation, part III: Induction of tolerance in the rigorous strain combination of Brown Norway donor to Lewis recipient

The complete withdrawal of immunosuppressive therapy after hind-limb transplantation across a strong histocompatibility barrier (Brown-Norway to Lewis) included a low-dose combination of FK506, mycophenolate mofetil (MMF), and prednisone. MMF and prednisone were tapered and withdrawn between weeks 2 and 7. From weeks 8 to 24, Group 1 animals (n=23) had FK506 tapered; for those in Group 2 (n=11) the dose of FK506 was not changed. At week 24, FK506 was stopped. The six limb grafts in Group 1 (26%) that achieved the 1-year end-point uneventfully showed chimerism by bone marrow and skin grafting supporting the presence of donor-specific tolerance. Rejection, which was common during tapering of FK506, was reversed by salvage therapy. All limbs were rejected postwithdrawal in Group 2. This study showed that tapering of FK506 combined with salvage therapy may allow long-term survival of some transplanted limbs after complete withdrawal of immunosuppressive therapy despite a complete MHC barrier.

Clinical and histological safety assessment of rectocele repair using collagen mesh

AIM

To clinically and histologically evaluate inflammatory response following rectocele repair using porcine collagen mesh.

METHODS

Seventeen patients underwent rectocele repair using porcine collagen mesh. Inflammatory response was assessed by clinical and histological inflammatory grading pre- and postoperatively. Postoperative body temperature, complications and hospital stay was compared with 15 patients undergoing posterior colporraphy.

RESULTS

Postoperative clinical examination did not demonstrate any inflammatory reaction. There were no significant changes in fibroblast count (P = 0.43), connective tissue density grading (P = 0.54), macrophage count (P = 0.20), inflammatory cell count (P = 0.48), total cell count (P = 0.51), or inflammatory grading (P = 0.87) postoperatively compared with preoperative values. Body temperature was significantly elevated for both the study and control group, although higher for the study group, postoperatively day 1 (P < 0.001). There were no significant differences in hospital stay and postoperative complications.

CONCLUSION

Porcine collagen mesh was not associated with an adverse inflammatory response at clinical or histological evaluation and appears to be a safe material when used for rectocele repair.

Steroid- and ATG-resistant rejection after double forearm transplantation responds to Campath-1H

We herein report on immunological and histological observations in the first bilateral forearm transplant recipient. The last of three rejection episodes occurring on day 95 after transplantation was resistant to steroid and antithymocyte globulin (ATG) treatment. Histology demonstrated lymphocytic infiltrates, apoptotic and necrotic keratinocytes and focal desquamation of the epidermis. Therapy with Campath-1H, however, resulted in complete restitution of normal skin. This is the first report on a successful rescue therapy with Campath-1H in a severe, steroid- and ATG-resistant rejection. Hence, Campath-1H treatment might be a novel and powerful therapeutic option for multiresistant allograft rejection.

The Pathology of Full-thickness Cadaver Skin Transplant for Large Abdominal Defects

Closure of large abdominal defects after extensive abdominal surgery is a major technical surgical problem. Failure to close the abdomen leaves the patient at risk for grave complications. Full-thickness abdominal wall skin transplantation appears to solve this problem. This is the first time that detailed histopathologic features of skin abdominal wall transplantation from cadaver donors are described. Five adults and four children underwent 10 transplants because of large abdominal wall defects. Twenty-two posttransplantation skin specimens were evaluated during a mean follow-up of 23.5 weeks, and the findings were compared with the clinical appearance of the skin. Rejection was manifested as a maculopapular rash. The histologic features were categorized as perivascular infiltrates, epidermal changes, and stromal changes. A grading system is proposed based on the number of cases encountered: No rejection, grade 0 (n = 9): No perivascular infiltrates. Indeterminate for rejection, grade 1 (n = 2): Up to 10% of vessels show infiltrates of small lymphocytes. No eosinophils, large lymphocytes, spongiosis, epidermal, or stromal inflammation are seen. Mild rejection, grade 2 (n = 5): 11% to 50% of vessels are infiltrated by small lymphocytes. Eosinophils and mild spongiosis may or may not be present. No epidermal infiltrates, stromal infiltrates, or large lymphocytes are seen. Moderate rejection, grade 3 (n = 4): Greater than 50% of vessels show lymphocytic infiltrates that may be accompanied by epidermal and stromal inflammation. Spongiosis is absent or mild. Endothelial plumping, eosinophils, and large lymphocytes may be seen. Severe rejection, grade 4 (n = 2): Greater than 50% of vessels show infiltrates, but different from moderate rejection, there is dyskeratosis and the epidermis shows heavier lymphocytic infiltrates and moderate to severe spongiosis. The stroma shows infiltrates extending into the base of the epidermis. Endothelial plumping, eosinophils, and large lymphocytes are present. The mean number of weeks after transplantation for the development of clearcut rejection (grades 2-4) was 8.36. Among the 9 nonrejection cases, 4 specimens from 3 patients had thrombosis of the vessels feeding the graft. A grading system serves to better assess skin allograft rejection.

On the ethics of facial transplantation research

Transplantation continues to push the frontiers of medicine into domains that summon forth troublesome ethical questions. Looming on the frontier today is human facial transplantation. We develop criteria that, we maintain, must be satisfied in order to ethically undertake this as-yet-untried transplant procedure. We draw on the criteria advanced by Dr. Francis Moore in the late 1980s for introducing innovative procedures in transplant surgery. In addition to these we also insist that human face transplantation must meet all the ethical requirements usually applied to health care research. We summarize the achievements of transplant surgery to date, focusing in particular on the safety and efficacy of immunosuppressive medications. We also emphasize the importance of risk/benefit assessments that take into account the physical, aesthetic, psychological, and social dimensions of facial disfiguration, reconstruction, and transplantation. Finally, we maintain that the time has come to move facial transplantation research into the clinical phase.