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Siemionow M, Cwykiel J, Chambily L, Gacek S, Brodowska S. Novel Human Umbilical Di-Chimeric (HUDC) cell therapy for transplantation without life-long immunosuppression. Stem Cell Investig 2023; 10:16. [PMID: 37614644 PMCID: PMC10442563 DOI: 10.21037/sci-2023-024] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 08/02/2023] [Indexed: 08/25/2023]
Abstract
Background Cell-based therapies are promising for tolerance induction in bone marrow (BM), solid organs, and vascularized composite allotransplantation (VCA). The toxicity of bone marrow transplantation (BMT) protocols precludes this approach from routine clinical applications. To address this problem, we developed a new therapy of Human Umbilical Di-Chimeric (HUDC) cells for tolerance induction in transplantation. This study established in vitro characterization of the created HUDC cells. Methods We performed sixteen ex vivo polyethylene glycol (PEG)-mediated fusions of human umbilical cord blood (UCB) cells from two unrelated donors. Fusion feasibility was confirmed in vitro by flow cytometry (FC) and confocal microscopy (CM). The HUDC cells' genotype was assessed by lymphocytotoxicity test and short tandem repeat-polymerase chain reaction (STR-PCR) analysis, phenotype by FC, viability by LIVE/DEAD® assay, and apoptosis level by Annexin V staining. We used COMET assay to assess HUDC cells' genotoxicity after the fusion procedure. Clonogenic properties of HUDC cells were evaluated by colony forming unit (CFU) assay. Mixed lymphocyte reaction (MLR) assay assessed immunogenic and tolerogenic properties of HUDC cells. Results We confirmed the creation of HUDC cells from two unrelated human donors of UCB cells by FC and CM. Human leukocyte antigen (HLA) class I and II typing, and STR-PCR analysis of HUDC cells confirmed the presence of alleles and loci from both unrelated UCB donors (donor chimerism: 49%±8.3%, n=4). FC confirmed the hematopoietic phenotype of HUDC cells. We confirmed high HUDC cells' viability (0.47% of dead cells) and a low apoptosis level of fused HUDC cells (15.9%) compared to positive control of PKH-stained UCB cells (20.4%) before fusion. COMET assay of HUDC cells revealed a lack of DNA damage. CFU assay confirmed clonogenic properties of HUDC cells, and MLR assay revealed a low immunogenicity of HUDC cells. Conclusions This study confirmed creation of a novel HUDC cell line by ex vivo PEG-mediated fusion of UCB cells from two unrelated donors. The unique concept of creating a HUDC cell line, representing the genotype and phenotype of both, transplant donor and the recipient, introduces a promising approach for tolerance induction in BM, solid organs, and VCA transplantation.
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Siemionow M, Brodowska S, Różczka K, Roesler C. Creation of human hematopoietic chimeric cell (HHCC) line as a novel strategy for tolerance induction in transplantation. Stem Cell Investig 2022; 9:11. [PMID: 36619595 PMCID: PMC9813662 DOI: 10.21037/sci-2022-026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 11/21/2022] [Indexed: 12/24/2022]
Abstract
Background Cell-based and chimerism-based therapies represent a promising approach for tolerance induction in transplantation. We propose a new cell therapy of the ex vivo created human hematopoietic chimeric cells (HHCC) as an alternative approach to bone marrow (BM)-based therapies in support of solid organ and vascularized composite allotransplantation (VCA). This study aimed to characterize in vitro the phenotype, genotype, clonogenic, and tolerogenic properties of HHCC. Methods Thirty ex vivo fusions of CD34+ cells from two unrelated human BM donors were performed. CD34+ cells were stained separately with PKH26 and PKH67 membrane dyes and fused using polyethylene glycol (PEG). Creation of human HHCC and chimeric state was confirmed by flow cytometry (FC), confocal microscopy (CM) and electron microscopy (EM). HHCC's phenotype (CD34, CD133, CD117, CD4, CD19, CD4/CD25) was assessed by FC, viability by Trypan Blue, LIVE/DEAD and apoptosis by AnnexinV/Sytox Blue and TUNEL assay, while mixed lymphocyte reaction (MLR) assay assessed HHCC's immunogenicity and tolerogenic properties. HHCC differentiation, proliferation and clonogenic potential were assessed by the colony forming unit (CFU). Polyploidy was evaluated by fluorescence in situ hybridization (FISH), whereas polymerase chain reaction-reverse sequence-specific oligonucleotide probe (PCR-rSSOP) and short tandem repeats-polymerase chain reaction (STR-PCR) assessed HHCC's genotype, and chimerism. Reverse transcription polymerase chain reaction (RT-PCR) analyzed cytokines secretion [interleukin (IL)-10, transforming growth factor-β (TGF-β) and tumor necrosis factor-α (TNF-α)] up to 14 days post-fusion. Results FC and CM confirmed creation of HHCC by fusion of CD34+ cells from two unrelated human donors. After fusion, maintenance of hematopoietic markers and increased expression of Treg-cells (CD4/CD25) was confirmed. Moreover, high HHCC viability (99%) and a low apoptosis rate (1.2%) were revealed HHCC presented decreased immunogenicity by MLR, and significant, 40-fold increase of IL-10 the pro-tolerogenic cytokine at 21 days after fusion (RT-PCR) P<0.0001. The number of polyploid cells was negligible (0.48%). PCR-rSSOP of HHCC after fusion confirmed presence of human leukocyte antigen (HLA) class I and class II-alleles and presence of the loci specific for both CD34+ cells BM donors by STR-PCR. Conclusions We have created a new hematopoietic cell line of HHCC from two unrelated human donors, and have successfully characterized in vitro, viability, phenotype, genotype, clonogenic, and tolerogenic properties of HHCC. These unique immunomodulatory and tolerogenic properties introduce HHCC as a novel therapeutic approach for tolerance induction in VCA and solid organ transplantation.
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Jundziłł A, Klimczak A, Sonmez E, Brzezicki G, Siemionow M. The Positive Impact of Donor Bone Marrow Cells Transplantation into Immunoprivileged Compartments on the Survival of Vascularized Skin Allografts. Arch Immunol Ther Exp (Warsz) 2021; 69:28. [PMID: 34633538 PMCID: PMC8505373 DOI: 10.1007/s00005-021-00631-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 08/02/2021] [Indexed: 11/30/2022]
Abstract
Using the vascularized skin allograft (VSA) model, we compared the tolerogenic effects of different allogeneic bone marrow transplantation (BMT) delivery routes into immunoprivileged compartments under a 7-day protocol immunosuppressive therapy. Twenty-eight fully MHC mismatched VSA transplants were performed between ACI (RT1a) donors and Lewis (RT11) recipients in four groups of seven animals each, under a 7-day protocol of alfa/beta TCRmAb/CsA (alpha/beta-TCR monoclonal antibodies/Cyclosporine A therapy). Donor bone marrow cells (BMC) (100 × 106 cells) were injected into three different immunoprivileged compartments: Group 1: Control, without cellular supportive therapy, Group 2: Intracapsular BMT, Group 3: Intragonadal BMT, Group 4: Intrathecal BMT. In Group 2, BMC were transplanted under the kidney capsule. In Group 3, BMC were transplanted into the right testis between tunica albuginea and seminiferous tubules, and in Group 4, cells were injected intrathecally. The assessment included: skin evaluation for signs and grade of rejection and immunohistochemistry for donor cells engraftment into host lymphoid compartments. Donor-specific chimerism for MHC class I (RT1a) antigens and the presence of CD4+/CD25+ T cells were assessed in the peripheral blood of recipients. The most extended allograft survival, 50–78 days, was observed in Group 4 after intrathecal BMT. The T cells CD4+/CD25+ in the peripheral blood were higher after intrathecal BMC injection than other experimental groups at each post-transplant time point. Transplantation of BMC into immunoprivileged compartments delayed rejection of fully mismatched VSA and induction of robust, donor-specific chimerism.
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Affiliation(s)
- Arkadiusz Jundziłł
- Department of Regenerative Medicine, Cell and Tissue Bank, Ludwik Rydygier Medical College, Nicolaus Copernicus University in Torun, Bydgoszcz, Poland.,Department of Plastic, Reconstructive and Aesthetic Surgery, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Bydgoszcz, Poland.,Department of Plastic Surgery, Cleveland Clinic, Cleveland, OH, USA
| | - Aleksandra Klimczak
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland.,Department of Plastic Surgery, Cleveland Clinic, Cleveland, OH, USA
| | - Erhan Sonmez
- Department of Plastic Surgery, Cleveland Clinic, Cleveland, OH, USA.,Katip Çelebi Üniversity, Atatürk Training Hospital, Plastic and Reconstructive Surgery Clinic, İzmir, Turkey
| | - Grzegorz Brzezicki
- Department of Plastic Surgery, Cleveland Clinic, Cleveland, OH, USA.,Department of Neurosurgery, Virginia Commonwealth University, Richmond, VA, USA
| | - Maria Siemionow
- Department of Plastic Surgery, Cleveland Clinic, Cleveland, OH, USA. .,Department of Orthopaedics, The University of Illinois at Chicago, Chicago, IL, USA. .,Department of Surgery, University of Medical Sciences, Poznan, Poland.
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Cwykiel J, Jundzill A, Klimczak A, Madajka-Niemeyer M, Siemionow M. Donor Recipient Chimeric Cells Induce Chimerism and Extend Survival of Vascularized Composite Allografts. Arch Immunol Ther Exp (Warsz) 2021; 69:13. [PMID: 33970329 PMCID: PMC8110509 DOI: 10.1007/s00005-021-00614-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 04/08/2021] [Indexed: 11/30/2022]
Abstract
This study evaluated the efficacy of donor recipient chimeric cell (DRCC) therapy created by fusion of donor and recipient derived bone marrow cells (BMC) in chimerism and tolerance induction in a rat vascularized composite allograft (VCA) model. Twenty-four VCA (groin flaps) from MHC-mismatched ACI (RT1a) donors were transplanted to Lewis (RT1l) recipients. Rats were randomly divided into (n = 6/group): Group 1—untreated controls, Groups 2—7-day immunosuppression controls, Group 3—DRCC, and Group 4—DRCC with 7-day anti-αβTCR monoclonal antibody and cyclosporine A protocol. DRCC created by polyethylene glycol-mediated fusion of ACI and Lewis BMC were cultured and transplanted (2–4 × 106) to VCA recipients via intraosseous delivery route. Flow cytometry assessed peripheral blood chimerism while fluorescent microscopy and PCR tested the presence of DRCC in the recipient’s blood, bone marrow (BM), and lymphoid organs at the study endpoint (VCA rejection). No complications were observed after DRCC intraosseous delivery. Group 4 presented the longest average VCA survival (79.3 ± 30.9 days) followed by Group 2 (53.3 ± 13.6 days), Group 3 (18 ± 7.5 days), and Group 1 (8.5 ± 1 days). The highest chimerism level was detected in Group 4 (57.9 ± 6.2%) at day 7 post-transplant. The chimerism declined at day 21 post-transplant and remained at 10% level during the entire follow-up period. Single dose of DRCC therapy induced long-term multilineage chimerism and extended VCA survival. DRCC introduces a novel concept of customized donor-recipient cell-based therapy supporting solid organ and VCA transplants.
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Affiliation(s)
- Joanna Cwykiel
- Department of Orthopaedics, University of Illinois At Chicago, Molecular Biology Research Building, 900 S. Ashland Ave. Room# 3356, Chicago, IL, 60607, USA.,Department of Plastic Surgery, Cleveland Clinic, Cleveland, OH, USA
| | - Arkadiusz Jundzill
- Department of Plastic Surgery, Cleveland Clinic, Cleveland, OH, USA.,Chair of Urology, Department of Regenerative Medicine, Nicolaus Copernicus University in Torun, Ludwik Rydygier Medical College in Bydgoszcz, Bydgoszcz, Poland.,Department of Plastic, Reconstructive and Aesthetic Surgery, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Bydgoszcz, Poland
| | - Aleksandra Klimczak
- Department of Plastic Surgery, Cleveland Clinic, Cleveland, OH, USA.,Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
| | | | - Maria Siemionow
- Department of Orthopaedics, University of Illinois At Chicago, Molecular Biology Research Building, 900 S. Ashland Ave. Room# 3356, Chicago, IL, 60607, USA. .,Department of Plastic Surgery, Cleveland Clinic, Cleveland, OH, USA. .,Department of Surgery, Poznan University of Medical Sciences, Poznan, Poland.
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Zor F, Bozkurt M, Cwykiel J, Karagoz H, Kulahci Y, Uygur S, Siemionow M. The effect of thymus transplantation on donor-specific chimerism in the rat model of composite osseomusculocutaneous sternum, ribs, thymus, pectoralis muscles, and skin allotransplantation. Microsurgery 2020; 40:576-584. [PMID: 31904149 DOI: 10.1002/micr.30555] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 11/15/2019] [Accepted: 12/26/2019] [Indexed: 12/13/2022]
Abstract
INTRODUCTION Research on tolerance has proven that development of donor-specific chimerism (DSC) may accompany tolerance induction in vascularized composite allotransplantation (VCA). In this study, we aimed to determine the effect of thymus transplantation on the induction of DSC in rat VCA model of osseomusculocutaneous sternum (OMCS) and osseomusculocutaneous sternum and thymus (OMCST) allotransplantation. MATERIALS AND METHODS A total of 20 Lewis-Brown Norway and Lewis rats, 5-6 weeks old, weighting between 120 and 150 g, were used in the study. OMCS (n = 5) and OMCST (n = 5) allografts were harvested from Lewis-Brown Norway donors (RT1l + n ) based on the common carotid artery and external jugular vein, and a heterotopic transplantation was performed to the inguinal region of the Lewis (RT1l ) recipients under cyclosporine A monotherapy (16 mg/kg) protocol tapered to 2 mg/kg and maintained for the duration of the study. The peripheral blood chimerism levels (T-cell, B-cell, and monocyte/granulocyte/dendritic cell-MGDC populations) were evaluated at days 7, 14, 35, 63, 100, and 150 posttransplant by flow cytometry. At Day 150, thymus, spleen, and liver samples were assessed by polymerase chain reaction (PCR) in the presence of DSC. RESULTS Total chimerism level increased in both OMCST and OMCS groups at all time points. At 150 days posttransplant, chimerism in OMCST group was significantly higher (12.91 ± 0.16%) than that in OMCS group (8.89 ± 0.53%%, p < .01), and PCR confirmed the presence of donor-derived cells in the liver and spleen of all OMCST recipients and in one liver sample and two spleen samples in OMCS recipients without thymus transplant. CONCLUSIONS This study confirmed the direct effects of thymus transplantation on the induction and maintenance of DSC in T-cell, B-cell, and MGDC populations. These results confirm correlation between thymus transplantation and DSC induction.
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Affiliation(s)
- Fatih Zor
- Wake Forest Institute for Regenerative Medicine, Winston Salem, North Carolina.,Department of Plastic Surgery, Cleveland Clinic, Cleveland, Ohio
| | - Mehmet Bozkurt
- Department of Plastic Surgery, Cleveland Clinic, Cleveland, Ohio.,Department of Plastic and Reconstructive Surgery, Bagcilar Training and Research Hospital, Istanbul, Turkey
| | - Joanna Cwykiel
- Department of Plastic Surgery, Cleveland Clinic, Cleveland, Ohio.,Department of Orthopaedics, University of Illinois at Chicago, Chicago, Illinois
| | - Huseyin Karagoz
- Wake Forest Institute for Regenerative Medicine, Winston Salem, North Carolina.,Department of Orthopaedics, University of Illinois at Chicago, Chicago, Illinois
| | - Yalcin Kulahci
- Wake Forest Institute for Regenerative Medicine, Winston Salem, North Carolina.,Department of Plastic Surgery, Cleveland Clinic, Cleveland, Ohio
| | - Safak Uygur
- Department of Plastic Surgery, Cleveland Clinic, Cleveland, Ohio.,Department of Orthopaedics, University of Illinois at Chicago, Chicago, Illinois
| | - Maria Siemionow
- Department of Plastic Surgery, Cleveland Clinic, Cleveland, Ohio.,Department of Orthopaedics, University of Illinois at Chicago, Chicago, Illinois
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Sutter D, Dzhonova DV, Prost JC, Bovet C, Banz Y, Rahnfeld L, Leroux JC, Rieben R, Vögelin E, Plock JA, Luciani P, Taddeo A, Schnider JT. Delivery of Rapamycin Using In Situ Forming Implants Promotes Immunoregulation and Vascularized Composite Allograft Survival. Sci Rep 2019; 9:9269. [PMID: 31239498 PMCID: PMC6592945 DOI: 10.1038/s41598-019-45759-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 06/13/2019] [Indexed: 12/11/2022] Open
Abstract
Vascularized composite allotransplantation (VCA), such as hand and face transplantation, is emerging as a potential solution in patients that suffered severe injuries. However, adverse effects of chronic high-dose immunosuppression regimens strongly limit the access to these procedures. In this study, we developed an in situ forming implant (ISFI) loaded with rapamycin to promote VCA acceptance. We hypothesized that the sustained delivery of low-dose rapamycin in proximity to the graft may promote graft survival and induce an immunoregulatory microenvironment, boosting the expansion of T regulatory cells (Treg). In vitro and in vivo analysis of rapamycin-loaded ISFI (Rapa-ISFI) showed sustained drug release with subtherapeutic systemic levels and persistent tissue levels. A single injection of Rapa-ISFI in the groin on the same side as a transplanted limb significantly prolonged VCA survival. Moreover, treatment with Rapa-ISFI increased the levels of multilineage mixed chimerism and the frequency of Treg both in the circulation and VCA-skin. Our study shows that Rapa-ISFI therapy represents a promising approach for minimizing immunosuppression, decreasing toxicity and increasing patient compliance. Importantly, the use of such a delivery system may favor the reprogramming of allogeneic responses towards a regulatory function in VCA and, potentially, in other transplants and inflammatory conditions.
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Affiliation(s)
- Damian Sutter
- Department of Plastic and Hand Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | | | - Jean-Christophe Prost
- University Institute of Clinical Chemistry, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Cedric Bovet
- University Institute of Clinical Chemistry, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Yara Banz
- Institute of Pathology, University of Bern, Bern, Switzerland
| | - Lisa Rahnfeld
- Department of Pharmaceutical Technology, Institute of Pharmacy, University of Jena, Jena, Germany.,Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Jean-Christophe Leroux
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland
| | - Robert Rieben
- Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Esther Vögelin
- Department of Plastic and Hand Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Jan A Plock
- Department of Plastic Surgery and Hand Surgery, University Hospital Zurich, University of Zurich, Zürich, Switzerland.
| | - Paola Luciani
- Department of Pharmaceutical Technology, Institute of Pharmacy, University of Jena, Jena, Germany. .,Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland. .,Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland.
| | - Adriano Taddeo
- Department of Plastic and Hand Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland. .,Department for BioMedical Research, University of Bern, Bern, Switzerland.
| | - Jonas T Schnider
- Department of Plastic and Hand Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
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Fryer M, Grahammer J, Khalifian S, Furtmüller GJ, Lee WPA, Raimondi G, Brandacher G. Exploring cell-based tolerance strategies for hand and face transplantation. Expert Rev Clin Immunol 2015; 11:1189-204. [DOI: 10.1586/1744666x.2015.1078729] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Cellular Therapies via Vascularized Bone Marrow Transplantation. Plast Reconstr Surg 2015. [DOI: 10.1007/978-1-4471-6335-0_73] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Vascular Thymus and Hind Limb Allotransplantation Model. Plast Reconstr Surg 2015. [DOI: 10.1007/978-1-4471-6335-0_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Klimczak A, Siemionow MZ. Cellular Therapies in Vascularized Composite Allograft: Review. Plast Reconstr Surg 2015. [DOI: 10.1007/978-1-4471-6335-0_70] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Cellular Therapies in Vascularized Composite Allograft. Plast Reconstr Surg 2015. [DOI: 10.1007/978-1-4471-6335-0_74] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Willems WF, Larsen M, Friedrich PF, Bishop AT. Vascularized bone transplant chimerism mediated by vascular endothelial growth factor. Microsurgery 2015; 35:45-51. [PMID: 25073635 PMCID: PMC4308546 DOI: 10.1002/micr.22300] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Revised: 07/09/2014] [Accepted: 07/14/2014] [Indexed: 11/12/2022]
Abstract
BACKGROUND Vascular endothelial growth factor (VEGF) induces angiogenesis and osteogenesis in bone allotransplants. We aim to determine whether bone remodeling in VEGF-treated bone allotransplants results from repopulation with circulation-derived autogenous cells or survival of allogenic transplant-derived cells. METHODS Vascularized femoral bone transplants were transplanted from female Dark Agouti rats (DA;RT1(a) ) to male Piebald Viral Glaxo (PVG;RT1(c) ). Arteriovenous bundle implantation and short-term immunosuppression were used to maintain cellular viability. VEGF was encapsulated in biodegradable microspheres and delivered intramedullary in the experimental group (n = 22). In the control group (n = 22), no VEGF was delivered. Rats were sacrificed at 4 or 18 weeks. Laser capture microdissection of bone remodeling areas was performed at the inner and outer cortex. Sex-mismatched genes were quantified with reverse transcription-polymerase chain reaction to determine the amount of male cells to total cells, defined as the relative expression ratio (rER). RESULTS At 4 weeks, rER was significantly higher at the inner cortex in VEGF-treated transplants as compared to untreated transplants (0.622 ± 0.225 vs. 0.362 ± 0.081, P = 0.043). At 4 weeks, the outer cortex in the control group had a significantly higher rER (P = 0.038), whereas in the VEGF group, the inner cortex had a higher rER (P = 0.015). Over time, in the outer cortex the rER significantly increased to 0.634 ± 0.106 at 18 weeks in VEGF-treated rats (P = 0.049). At 18 weeks, the rER was >0.5 at all cortical areas in both groups. CONCLUSIONS These in vivo findings suggest a chemotactic effect of intramedullary applied VEGF on recipient-derived bone and could imply that more rapid angiogenesis of vascularized allotransplants can be established with microencapsulated VEGF.
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Affiliation(s)
- Wouter F Willems
- Department of Orthopedic Surgery, Microvascular Research Laboratory, Mayo Clinic, Rochester, MN
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