Recipient Epithelium Research Articles

Tracheal transplantation: lessons learned that may apply to lung transplantation.

The purpose of this review is to explore the lessons learned from experimental and human tracheal transplantation to determine if this information may be applied to lung transplantation. Experimental work in animal models and the recent human tracheal transplantation suggests that a robust tracheal vascular supply prevents anastomotic complications. Further, this work demonstrates that tracheal allografts undergo a progressive chimerism as recipient epithelium repopulates the allograft. In contrast to most vascularized composite allografts such as hand and face transplantation that experience high rates of rejection, the tracheal allograft did not demonstrate rejection. This may suggest that tissue chimerism plays a role in evading immune-mediated allograft rejection. While anastomotic complications and chronic allograft rejection are the most common complications related to lung transplantation, the findings associated with tracheal transplantation may have implications for both reducing complications associated with lung transplantation.

Organoids transplantation as a new modality to design epithelial signature to create a membrane-protective sulfomucin-enriched segment.

The organoids therapy for ulcerative colitis (UC) is under development. It is important to dissect how the engrafted epithelium can provide benefits for overcoming the vulnerability to inflammation. We mainly focused on the deliverability of sulfomucin, which is reported to play an important role in epithelial function. We analyzed each segment of colon epithelium to determine differences in sulfomucin production in both mice and human. Subsequently, we transplanted organoids established from sulfomucin-enriched region into the injured recipient epithelium following dextran sulfate sodium-induced colitis and analyzed the engrafted epithelium in mouse model. In human normal colon, sulfomucin production was increased in proximal colon, whereas it was decreased in the inflammatory region of UC. In murine colon epithelium, increased sulfomucin production was found in cecum compared to distal small intestine and proximal colon. RNA sequencing analysis revealed that several key genes associated with sulfomucin production such as Papss2 and Slc26a1 were enriched in isolated murine cecum crypts. Then we established murine cecum organoids and transplanted them into the injured epithelium of distal colon. Although the expression of sulfomucin was temporally decreased in cecum organoids, its secretion was restored again in the engrafted patches after transplantation. Finally, we verified a part of mechanisms controlling sulfomucin production in human samples. This study illustrated the deliverability of sulfomucin in the disease-relevant grafting model to design sulfomucin-producing epithelial units in severely injured distal colon. The current study is the basis for the better promotion of organoids transplantation therapy for refractory UC.

Vascularized Tracheal Transplantation: A Twenty Month Follow Up.

Tracheal transplantation has been considered the ideal option for the reconstruction of long-segment circumferential tracheal defects. Our group developed a technique for vascularized single-staged tracheal transplantation. Twenty months ago, we performed the first-in-human tracheal transplantation. Herein, we report a twenty-month follow-up. The recipient presented with a 9.0 cm airway tracheal stenosis and complete cricoid stenosis. The patient previously failed six major conventional surgical procedures. Prior to transplantation, the patient's airway was maintained with an extended tracheostomy and stent. The patient experienced repeated life-threatening airway obstruction because of mucous plugging and obstructive granulation tissue. In January 2020 the patient underwent a single-staged tracheal transplantation treated with triple-therapy immunosuppression. Organ rejection was monitored with endoscopic tracheoscopy, narrow-band imaging, free-cell DNA assessment, and histological and cytogenetic analysis of tracheal biopsies. Mucociliary function was assessed with dye motility studies. Twenty months following transplantation, there has been no evidence of acute or chronic rejection. Since day 60, there has been no detectable free cell DNA, a surrogate marker for immune-mediated allograft rejection. Fluorescence in situ hybridization (FISH) cytogenetics demonstrated that the donor trachea was repopulated with recipient epithelium establishing a chimeric allograft. Narrow-band imaging demonstrates a well-vascularized epithelial mucosa and bronchoscopic biopsies demonstrate normal ciliated epithelial architecture and viable epithelial lining with functional ciliated epithelium. The patient has resumed a normal life without a stent or tracheostomy and has returned to work. Twenty months after single-staged vascularized tracheal transplantation, the trachea is functional and the patient breathes without the need for a tracheostomy or stent. Single-staged long-segment tracheal transplantation is a viable option for tracheal defects that are not amenable to conventional reconstructive techniques. 4 Laryngoscope, 133:1839-1845, 2023.

Prefabrication and Prelamination Strategies for the Reconstruction of Complex Defects of Trachea and Larynx

Complex tracheal and laryngeal defects can be reconstructed using prelamination and prefabrication techniques. Three clinical situations are described in detail in the article. In short segment restenosis defects within scarred surroundings, we restore the fibrocartilaginous defect with a radial forearm fascia flap prelaminated with buccal mucosa or cartilage. This provides a newly vascularized inner lining to the tracheal defect and restores the tubular convexity. For long segment defects we need a technique that can withstand respiratory forces. We use a heterotopic prefabrication strategy to vascularize a tracheal allograft wrapped in forearm fascia. Chimerism is created by replacing donor respiratory epithelium with buccal mucosa of the recipient. After orthotopic transfer, this chimerism allows immunosuppression to be tapered and stopped when bronchoscopy shows mucosal integrity of the new trachea, since the recipient epithelium replaces the allogeneic inner tracheal lining by means of a chronic rejection process. A distinct situation occurs after resection of a unilateral larynx tumor, which usually results in a total laryngectomy with loss of both vocal cords, since reconstruction of the hemilarynx is considered too complex. First, we prefabricate a nearby four-ring autologous tracheal segment using radial forearm fascia. In a second stage, this orthotopically vascularized trachea restores the laryngeal structure with the aim to conserve one vocal cord and thus speech. Orthotopic and heterotopic prelamination and prefabrication strategies offer efficient and reproducible solutions for the restoration of challenging short and long segment tracheal defects, as well as unilateral laryngeal defects. The series in this review article are based on previous studies and case reports. The level of evidence is III-"Study of nonconsecutive patients, without a universally applied gold standard: case-control study".

Immunohistochemical study of jejunal graft mucosa cell populations during the initial adaptation phase in the host body in rats

The character of the changes in cell populations within the jejunal graft mucosa during the initial adaptation phase in the host body was investigated. 24 adult male Wistar rats underwent intestinal heterotopic allotransplantation. Aorto-aortal and porto-caval anastomoses were performed using the end-to-side microsurgery technique. Graft tissues were compared to the intestinal tissues of the recipients. This study demonstrates that: (1) Distinct injury to the graft mucosa 1h after transplantation was accompanied by significant reduction in numbers of epithelial secretory cell populations. The injury was more intense in the mesenteric portion. Six hours after transplantation the graft mucosa was covered by a continuous epithelium, but the number of goblet and Paneth cells was found to be less than 30% of that in the recipient epithelium. (2) In comparison with recipients, myeloperoxidase-positive cell numbers increased significantly in the graft mucosa 1h after transplantation. In the epithelial layer, denudation and destruction of villi was associated with a significant reduction in intraepithelial lymphocyte numbers. A significant decrease in mucosal mast cell numbers was detected 6h after transplantation. They attained only 10% of the number found in the recipients. (3) Time-dependent changes in the graft mucosa revealed that CD163-positive cells increased significantly in the graft mucosa during 6h after transplantation and reached the level found in the recipients. In contrast, the myeloperoxidase-positive cell population significantly decreased in the graft mucosa within the initial 6h.

Survival of Donor-Derived Cells in Human Corneal Transplants

To determine the fate of donor epithelial, stromal, and endothelial cells after corneal transplantation in humans. Fifty-two transplanted corneal buttons were explanted over a 2-year period from patients who required regrafting and had received corneas from donors of opposite sex. Fluorescence in situ hybridization of the sex chromosomes of the epithelial, stromal, and endothelial cells was performed in histologic sections prepared from each freshly explanted graft. Fluorescence microscopy was subsequently used to determine the origin of cells in the graft (donor or recipient) and to quantify the relative proportion of donor and recipient cells of each corneal cell type. As early as 3 months after transplantation, donor epithelial cells were completely replaced by recipient epithelium in all corneal buttons examined. Donor stromal and endothelial cells, however, were found in all 52 buttons, with 4% to 95% of stromal cells and 6% to 95% of endothelial cells being of donor origin. No significant correlation between donor cell proportion and the age of the graft could be found. Donor-derived cells were found in significant numbers up to 32 years after transplantation. Eight corneas in this study were transparent, compensated grafts, and a similar long-term survival of donor stromal and endothelial cells was found in these cases. Although donor epithelial cells are promptly replaced, a high proportion of donor stromal and endothelial cells can survive within the corneal transplant in the long-term. The proportion of surviving donor cells is highly variable; however, the source of this variability remains unknown.

Donor corneas for transplantation: a scanning electron microscopic study of the epithelium

Donor corneas are processed in eye banks and used for transplantation as a standard routine. The maximum time limit post-mortem for harvesting donor tissue varies greatly between eye banks. This study aimed to examine the corneal epithelium for structural changes post-mortem. A total of 51 corneas harvested between 14 and 163 hours post-mortem were examined using scanning electron and light microscopy. Cell loss occurred through desquamation of flat superficial cells during the first days. In corneas with a post-mortem time of more than 2-3 days, large superficial cell sheets and deeper cells detached, starting centrally. Deep peripheral cells remained. The loss of the superficial cells revealed the 3-dimensional structure of the epithelium and the membrane characteristics of deeper cells. The longer the time post-mortem, the greater the epithelial cell loss. However, a rim of peripheral cells remained, even after 7 days. The superficial cell layer showed signs of strong lateral attachment and broke up in a sheet-like fashion. The intercellular adhesion between deeper cells and adhesion between the basal cells and the basement membrane appeared to be weak post-mortem. The cell membrane structures of the remaining cells were surprisingly well retained. The clinical implication of the study is discussed.

Therapeutic Use of Limbal Stem Cells

Stem cells are defined as relatively undifferentiated cells that have the capacity to generate more differentiated daughter cells. Limbal stem cells are responsible for epithelial tissue repair and regeneration throughout the life. Limbal stem cells have been localized to the Palisades of Vogt in the limbal region. Limbal stem cells have a higher proliferative potential compared to the cells of peripheral and central cornea. Limbal stem cells have the capacity to maintain normal corneal homeostasis. However, in some pathological states, such as chemical and thermal burns, Stevens-Johnson syndrome, and ocular pemphigoid limbal stem cells fail to maintain the corneal epithelial integrity. In such situations, limbal stem cell transplantation has been required as a therapeutic option. In unilateral disorders, the usual source of stem cells is the contralateral eyes, but if the disease is bilateral stem cell allografts have to be dissected from family members or cadaver eyes. The advent of ex vivo expansion of limbal stem cells from a small biopsy specimen has reduced the risk of limbal deficiency in the donor eye. Concomitant immunosuppressive therapy promotes donor-derived epithelial cell viability, but some evidences suggest that donor-derived epithelial stem cell viability is not sustained indefinitely. Thus, long-term follow-up studies are required to ascertain whether donor limbal stem cell survival or promotion of recolonization by resident recipient stem cells occurs in restored recipient epithelium. However, this is not an easy task since a definitive limbal stem cell marker has not been identified yet. This review will discuss the therapeutic usage of limbal stem cells in the corneal epithelial disorders.

Descemet's Stripping With Endothelial Keratoplasty in 50 Eyes: A Refractive Neutral Corneal Transplant

ABSTRACT PURPOSE: To evaluate early visual and refractive outcomes following treatment of corneal endothelial dysfunction with a corneal transplantation technique, Descemet's stripping with endothelial keratoplasty (DSEK). METHODS: Visual and refractive outcomes of the first 50 consecutive cases of DSEK performed by a single surgeon between December 2003 and July 2004 were analyzed retrospectively. The DSEK technique consisted of stripping Descemet's membrane and endothelium from a recipient cornea and transplanting the posterior stroma and endothelium of a donor cornea through a 5-mm incision. RESULTS: Results are reported for 50 eyes in 47 patients (30 women and 17 men). Mean patient age at surgery was 70±12 years (range: 34 to 89 years). Five eyes were treated for corneal edema or bullous keratopathy and 45 for Fuchs' endothelial dystrophy. Seven eyes were phakic and 43 were Pseudophakic. Six months after surgery, mean manifest cylinder was 1.5±0.94 diopters (D), unchanged from preoperative cylinder of 1.5±1.0 D. Mean manifest spherical equivalent refraction was 0.15 ±1.5 D at 6-month follow-up compared with -0.36±1.4 D preoperatively (P=.10) At 3- and 6-month follow-up, significant improvement was noted in mean best spectacle-corrected visual acuity compared with the preoperative mean of 20/100 (P=.007). At 6-month follow-up, 31 (62%) eyes refracted to ≥20/40 and 38 (76%) eyes saw ≥20/50. CONCLUSIONS: Compared to standard penetrating keratoplasty, DSEK causes minimal refractive change and provides rapid visual recovery for patients with endothelial dysfunction. This technique maintains the structural integrity of the cornea by preserving the recipient's epithelium, Bowman's layer, and entire stromal thickness. [J Refract Surg. 2005;21:339-345.]

Descemet's Stripping With Endothelial Keratoplasty in 50 Eyes: A Refractive Neutral Corneal Transplant/Reply

To evaluate early visual and refractive outcomes following treatment of corneal endothelial dysfunction with a corneal transplantation technique, Descemet's stripping with endothelial keratoplasty (DSEK). Visual and refractive outcomes of the first 50 consecutive cases of DSEK performed by a single surgeon between December 2003 and July 2004 were analyzed retrospectively. The DSEK technique consisted of stripping Descemet's membrane and endothelium from a recipient cornea and transplanting the posterior stroma and endothelium of a donor cornea through a 5-mm incision. Results are reported for 50 eyes in 47 patients (30 women and 17 men). Mean patient age at surgery was 70 +/- 12 years (range: 34 to 89 years). Five eyes were treated for corneal edema or bullous keratopathy and 45 for Fuchs' endothelial dystrophy. Seven eyes were phakic and 43 were pseudophakic. Six months after surgery, mean manifest cylinder was 1.5 +/- 0.94 diopters (D), unchanged from preoperative cylinder of 1.5 +/- 1.0 D. Mean manifest spherical equivalent refraction was 0.15 +/- 1.5 D at 6-month follow-up compared with -0.36 +/- 1.4 D preoperatively (P = .10) At 3- and 6-month follow-up, significant improvement was noted in mean best spectacle-corrected visual acuity compared with the preoperative mean of 20/100 (P = .007). At 6-month follow-up, 31 (62%) eyes refracted to > or = 20/40 and 38 (76%) eyes saw > or = 20/50. Compared to standard penetrating keratoplasty, DSEK causes minimal refractive change and provides rapid visual recovery for patients with endothelial dysfunction. This technique maintains the structural integrity of the cornea by preserving the recipient's epithelium, Bowman's layer, and entire stromal thickness.

Epithelial regeneration and preservation of tracheal cartilage after tracheal replacement with cryopreserved allograft in the rat

Objective: We investigated the origin of the epithelium in transplanted cryopreserved tracheal allografts in rats and tried to clarify the mechanism by which immunogenicity is reduced in this procedure. Methods: Tracheal transplantation was performed with PVG rats (allele at the RT1 locus: c) used as donors and ACI rats (allele at the RT1 locus: a) as recipients. After resection of a 5-ring segment of the cervical trachea of an ACI rat, the trachea was reconstructed with the cryopreserved tracheal segment of a PVG rat ( n = 6). No immunosuppressive agents or steroids were given. Histologic changes were determined and immunohistochemical staining was performed to investigate major histocompatibility complex class I antigens of the transplanted tracheal segment. Results: Two months after tracheal transplantation, 6 surviving ACI rats were killed. Histologically, the epithelium and tracheal cartilage of the transplanted cryopreserved segment displayed normal structure. Immunohistochemical staining showed that the major histocompatibility complex class I antigen of the ACI rat was expressed in the epithelium of the transplanted segment and that the class I antigen of the PVG rat was expressed in the cartilage of the transplanted segment. Conclusions: After transplantation of the cryopreserved trachea, the epithelium of the transplanted cryopreserved segment originated from the recipient epithelium whereas the cartilage retained the structure of the donor trachea. We hypothesize that transplantation of a cryopreserved trachea leads to the growth of the recipient's epithelium over the donor trachea, thereby reducing the antigenicity of the transplant. (J Thorac Cardiovasc Surg 1998;116:624-7)

Prevention of Obliterative Airway Disease (OAD) without Immunosuppression in Heterotopic Rat Tracheal Allografts: Anastomosis of Recipient Trachea to Donor Trachea Enables Re-epithelialization of Allografts by Recipient Epithelium

Prevention of Obliterative Airway Disease (OAD) without Immunosuppression in Heterotopic Rat Tracheal Allografts: Anastomosis of Recipient Trachea to Donor Trachea Enables Re-epithelialization of Allografts by Recipient Epithelium

Prevention of Obliterative Airway Disease (OAD) without Immunosuppression in Heterotopic Rat Tracheal Allografts: Anastomosis of Recipient Trachea to Donor Trachea Enables Re-epithelialization of Allografts by Recipient Epithelium

Prevention of Obliterative Airway Disease (OAD) without Immunosuppression in Heterotopic Rat Tracheal Allografts: Anastomosis of Recipient Trachea to Donor Trachea Enables Re-epithelialization of Allografts by Recipient Epithelium

The Biology of Skin Grafts

Skin grafting is commonly used to treat nonhealing wounds. However, how skin grafts help to heal wounds is not entirely known. Why epithelium from grafted skin is able to migrate and cover these wounds, while epithelium at the edge of nonhealing wounds is unable to, is a long unanswered biologic question. The recent use of cultured epithelial allografts has rekindled interest in the biology of skin grafts. Replaced, even in chronic wounds, by recipient epithelium, cultured epithelial allografts appear to work by providing a potent stimulus to healing imparted by the graft itself. Based on this, we have reassessed how skin autografts help to heal wounds and hypothesize that, in a similar fashion, autografts may work not only by replacing tissue but also by providing a stimulus for healing. We suggest that skin grafts may work not only as tissue replacement but as pharmacologic agents that provide a stimulus for healing. We believe that, someday, it may be possible to augment the stimulatory properties of donor skin to speed healing of the recipient wound.

The biology of skin grafts. Skin grafts as pharmacologic agents

<h3>† Background.—</h3> Skin grafting is commonly used to treat nonhealing wounds. However, how skin grafts help to heal wounds is not entirely known. Why epithelium from grafted skin is able to migrate and cover these wounds, while epithelium at the edge of nonhealing wounds is unable to, is a long unanswered biologic question. <h3>Observations.—</h3> The recent use of cultured epithelial allografts has rekindled interest in the biology of skin grafts. Replaced, even in chronic wounds, by recipient epithelium, cultured epithelial allografts appear to work by providing a potent stimulus to healing imparted by the graft itself. Based on this, we have reassessed how skin autografts help to heal wounds and hypothesize that, in a similar fashion, autografts may work not only by replacing tissue but also by providing a stimulus for healing. <h3>Conclusions.—</h3> We suggest that skin grafts may work not only as tissue replacement but as pharmacologic agents that provide a stimulus for healing. We believe that, someday, it may be possible to augment the stimulatory properties of donor skin to speed healing of the recipient wound. (<i>Arch Dermatol.</i>1993;129:481-483)

Double vital staining of corneal epithelium after corneal transplantation with a rose bengal-fluorescein mixture.

Longitudinal double vital staining with 1% rose bengal (RB) and 1% fluorescein (Flu) has been carried out on 33 eyes subjected to penetrating corneal transplantation. At the conclusion of the operation pronounced desiccation of both donor's and recipient's epithelium was seen in a scant 50%, but abrasion in only 8%. the desiccation subsided during the first post-operative day, but the donor's epithelium was rejected in the majority (91%). Healing started on the third day, manifesting itself by Flu-punctate whorl-shaped epithelium invading or gliding across the wound. By the fifth day nearly complete healing had occurred. In 9% no renewal of epithelium was noticed. Subsequent control examinations revealed loose sutures (RB-stained mucous adhesions), evanescent cicatricial defects, and open suture canals (Flu). Graft rejection occurred in 8 cases. In 5 of these, well-defined massive peripheral staining of donor epithelium was seen (RB most widespread and sharply outlined), and in the remaining 3, uncharacteristic, diffuse, punctate staining.

The Use of Epikeratophakia Grafts in Pediatric Monocular Aphakia

Epikeratophakia is a form of refractive surgery in which the recipient's epithelium is removed and a pre-shaped donor lenticule is sutured to the patient's cornea. Seventeen patients ranging in age from two months to 6.6 years received 19 epikeratophakia grafts for the correction of aphakic vision. The correction provided by the graft in combination with vigorous amblyopia therapy has yielded some improvement in vision in the 12 patients with successful grafts. This procedure may be particularly suitable for pediatric aphakic patients because it is extraocular and reversible and may be employed as a secondary procedure or in conjunction with cataract extraction. Only with longer follow-up of these and additional patients can these preliminary results be validated and the risk/benefit ratio of this procedure be assessed.

Epikeratophakia: the surgical correction of aphakia. II. Preliminary results in a non-human primate model.

We have developed a new form of refractive surgery, epikeratophakia, in which a disc of donor corneal tissue is lathed to a specific dioptric power and sutured on top of the recipient's cornea after the recipient epithelium has been removed. The optical correction obtained with epikeratophakia should be similar in quality to that of a contact lens, but would be permanent and would require no maintenance. A non-human primate model was used to test the predictability, stability, and clarity of epikeratophakia grafts. After surgery, the grafts did not always re-epithelialize readily; this problem has been solved with the use of a small, steep, soft bandage contact lens. For the nine month period of this study, the epikeratophakia grafts have remained clear and the curvatures of the anterior surfaces have remained constant. However, the actual visual potential of these grafts can be evaluated only by a controlled clinical study in humans.