Mesenchymal Stem/Stromal Cells Derived from Human and Animal Perinatal Tissues-Origins, Characteristics, Signaling Pathways, and Clinical Trials

Mesenchymal stem/stromal cells (MSCs) are currently one of the most extensively researched fields due to their promising opportunity for use in regenerative medicine. There are many sources of MSCs, of which cells of perinatal origin appear to be an invaluable pool. Compared to embryonic stem cells, they are devoid of ethical conflicts because they are derived from tissues surrounding the fetus and can be safely recovered from medical waste after delivery. Additionally, perinatal MSCs exhibit better self-renewal and differentiation properties than those derived from adult tissues. It is important to consider the anatomy of perinatal tissues and the general description of MSCs, including their isolation, differentiation, and characterization of different types of perinatal MSCs from both animals and humans (placenta, umbilical cord, amniotic fluid). Ultimately, signaling pathways are essential to consider regarding the clinical applications of MSCs. It is important to consider the origin of these cells, referring to the anatomical structure of the organs of origin, when describing the general and specific characteristics of the different types of MSCs as well as the pathways involved in differentiation.

Three-dimensional human placenta-like bud synthesized from induced pluripotent stem cells

Placental dysfunction is related to the pathogenesis of preeclampsia and fetal growth restriction, but there is no effective treatment for it. Recently, various functional three-dimensional organs have been generated from human induced-pluripotent cells (iPSCs), and the transplantation of these iPSCs-derived organs has alleviated liver failure or diabetes mellitus in mouse models. Here we successfully generated a three-dimensional placental organ bud from human iPSCs. The iPSCs differentiated into various lineages of trophoblasts such as cytotrophoblast-like, syncytiotrophoblast-like, and extravillous trophoblast-like cells, forming organized layers in the bud. Placental buds were transplanted to the murine uterus, where 22% of the buds were successfully engrafted. These iPSC-derived placental organ buds could serve as a new model for the study of placental function and pathology.

Human placental-derived stem cell therapy ameliorates experimental necrotizing enterocolitis

Necrotizing enterocolitis (NEC), a life-threatening intestinal disease, is becoming a larger proportionate cause of morbidity and mortality in premature infants. To date, therapeutic options remain elusive. Based on recent cell therapy studies, we investigated the effect of a human placental-derived stem cell (hPSC) therapy on intestinal damage in an experimental NEC rat pup model. NEC was induced in newborn Sprague-Dawley rat pups for 4 days via formula feeding, hypoxia, and LPS. NEC pups received intraperitoneal (ip) injections of either saline or hPSC (NEC-hPSC) at 32 and 56 h into NEC induction. At 4 days, intestinal macroscopic and histological damage, epithelial cell composition, and inflammatory marker expression of the ileum were assessed. Breastfed (BF) littermates were used as controls. NEC pups developed significant bowel dilation and fragility in the ileum. Further, NEC induced loss of normal villi-crypt morphology, disruption of epithelial proliferation and apoptosis, and loss of critical progenitor/stem cell and Paneth cell populations in the crypt. hPSC treatment improved macroscopic intestinal health with reduced ileal dilation and fragility. Histologically, hPSC administration had a significant reparative effect on the villi-crypt morphology and epithelium. In addition to a trend of decreased inflammatory marker expression, hPSC-NEC pups had increased epithelial proliferation and decreased apoptosis when compared with NEC littermates. Further, the intestinal stem cell and crypt niche that include Paneth cells, SOX9+ cells, and LGR5+ stem cells were restored with hPSC therapy. Together, these data demonstrate hPSC can promote epithelial healing of NEC intestinal damage.NEW & NOTEWORTHY These studies demonstrate a human placental-derived stem cell (hPSC) therapeutic strategy for necrotizing enterocolitis (NEC). In an experimental model of NEC, hPSC administration improved macroscopic intestinal health, ameliorated epithelial morphology, and supported the intestinal stem cell niche. Our data suggest that hPSC are a potential therapeutic approach to attenuate established intestinal NEC damage. Further, we show hPSC are a novel research tool that can be utilized to elucidate critical neonatal repair mechanisms to overcome NEC.

A Prospective, Single-center, Open-label Case Series Evaluating the Clinical Outcomes of Lyopreserved Placental Membrane Containing Viable Cells in the Treatment of Chronic Wounds

INTRODUCTION

Cryopreserved placental membrane containing viable cells (vCPM) in conjunction with standard of care (SOC) has shown clinical effectiveness in several studies for the management of acute and chronic wounds. Recently, a new lyophilization technique has been developed that allows viable tissues to be stored at room temperature as a structural and functional equivalent to vCPM.

OBJECTIVE

This case series evaluates the clinical outcomes of a lyopreserved placental membrane containing viable cells (vLPM) for the management of chronic wounds of various etiologies.

MATERIALS AND METHODS

Eleven patients (11 wounds: 5 diabetic foot ulcers, 5 venous leg ulcers, and 1 pressure ulcer) received weekly vLPM applications adjunct to SOC.

RESULTS

By week 12 of treatment, 63.6% (7/11) of patients achieved complete wound closure, with a mean time to closure of 47.1 days and a mean of 6 vLPM applications. Further, there were no adverse events attributed to vLPM.

CONCLUSIONS

This is the first case series reporting the clinical outcomes of vLPM for the management of chronic wounds. Results of this study demonstrate similar closure rates to those previously reported for vCPM. These results suggest potential clinical equivalence between the 2 formulations, with vLPM providing the added convenience of long-term room-temperature storage (current shelf life of 12 months).

Stage IV Perineal Pressure Ulcers in Immobile Patients Treated With Surgical Flap Closure Augmented With Cryopreserved Placental Membrane Containing Viable Cells

INTRODUCTION

Surgical closure of late-stage pressure ulcers (PUs) poses challenges in the immobilized population due to the high rate of complications, including infection, dehiscence, and recurrence. Muscle flap closure is the standard treatment for chronic, late-stage (stage 4) PUs, characterized by the European Pressure Ulcer Advisory Panel and National Pressure Ulcer Advisory Panel as full-thickness tissue loss with exposure of bone, tendon, or muscle.

OBJECTIVE

The aim of this study is to evaluate the outcomes associated with the use of a cryopreserved placental membrane containing viable cells (vCPM) graft for the augmentation of surgical flap closure in nonhealing perineal ulcers.

MATERIALS AND METHODS

Four paraplegic patients (2 men, 2 women; average age, 61 years; range, 44-77 years) with stage IV PUs (ischial, gluteal, and sacral areas) with a mean duration of 4 years (range, 0.5-10 years) received muscle flap closure augmented with vCPM. Following surgical debridement, vCPM was placed between the wound bed and muscle flap closure prior to skin closure. Patients were kept offloaded in fluid-air beds for 6 weeks followed by a gradual return to mobilization.

RESULTS

All 4 patients achieved complete wound closure in an average of 7 weeks (range, 6-8 weeks) without complications or recurrence. All patients demonstrated complete take of the muscle flap and maintained their closed wounds for an average follow-up of 12 months.

CONCLUSIONS

Preliminary clinical results indicate vCPM supports surgical wound closure of chronic perineal PUs in immobile, high-risk patients. In an effort to decrease postoperative recovery time and reduce complications, vCPM may be beneficial for patients undergoing perineal muscle flap closure.

Surgical Application of Viable Cryopreserved Placental Membrane for the Treatment of Chronic Wounds in 12 High-risk Patients

Treatment of lower extremity ulcers remains a challenge to physicians and surgeons. These wounds lead to an increased risk of amputation and increased mortality rate and must be treated aggressively, in many cases requiring surgical debridement, to prevent these complications. The objective of this retrospective case series is to evaluate the safety and efficacy of a viable cryopreserved placental membrane (vCPM) in 12 patients with 16 wounds of mixed etiologies when surgically debrided and augmented with vCPM 1 time, followed by standard of care (nonadherent dressing, gauze, and compression) until healed. The results of this case series demonstrate that the surgical application of vCPM can be used as an alternative treatment for high-risk patients with chronic lower extremity wounds.

Open-label Extension Phase of a Chronic Diabetic Foot Ulcer Multicenter, Controlled, Randomized Clinical Trial Using Cryopreserved Placental Membrane

OBJECTIVE

The results of the single-arm, open-label extension phase of the Grafix (cryopreserved placental membrane; CPM; Osiris Therapeutics, Inc, Columbia, MD) multicenter, blinded, randomized, controlled clinical trial for chronic diabetic foot ulcers (DFUs) is reported.

MATERIALS AND METHODS

Twenty-six patients in the standard wound care (SWC) arm whose DFUs did not close in the blinded phase chose to receive weekly applications of the CPM in an open-label extension phase.

RESULTS

In the extension phase, 17 (65.4%) patients closed their wounds in a median of 34 days and 3 visits. There were fewer total adverse events (AEs) (24 CPM vs. 52 SWC) and index wound-related infections (5 CPM vs. 12 SWC) during the CPM application compared with the number of AEs for the same patients during the SWC treatment in the blinded phase of the trial.

CONCLUSIONS

These results corroborate the benefits of this CPM combined with SWC over SWC alone for chronic DFUs previously reported for the blinded randomized phase of the trial, which directly relate to lower health care costs.

Decellularized human placenta supports hepatic tissue and allows rescue in acute liver failure

Tissue engineering with scaffolds to form transplantable organs is of wide interest. Decellularized tissues have been tested for this purpose, although supplies of healthy donor tissues, vascular recellularization for perfusion, and tissue homeostasis in engineered organs pose challenges. We hypothesized that decellularized human placenta will be suitable for tissue engineering. The universal availability and unique structures of placenta for accommodating tissue, including presence of embedded vessels, were major attractions. We found decellularized placental vessels were reendothelialized by adjacent native cells and bridged vessel defects in rats. In addition, implantation of liver fragments containing all cell types successfully hepatized placenta with maintenance of albumin and urea synthesis, as well as hepatobiliary transport of ^99m Tc-mebrofenin, up to 3 days in vitro. After hepatized placenta containing autologous liver was transplanted into sheep, tissue units were well-perfused and self-assembled. Histological examination indicated transplanted tissue retained hepatic cord structures with characteristic hepatic organelles, such as gap junctions, and hepatic sinusoids lined by endothelial cells, Kupffer cells, and other cell types. Hepatocytes in this neo-organ expressed albumin and contained glycogen. Moreover, transplantation of hepatized placenta containing autologous tissue rescued sheep in extended partial hepatectomy-induced acute liver failure. This rescue concerned amelioration of injury and induction of regeneration in native liver. The grafted hepatized placenta was intact with healthy tissue that neither proliferated nor was otherwise altered.

CONCLUSION

The unique anatomic structure and matrix of human placenta were effective for hepatic tissue engineering. This will advance applications ranging from biological studies, drug development, and toxicology to patient therapies. (Hepatology 2018;67:1956-1969).

Application of Viable Cryopreserved Human Placental Membrane Grafts in the Treatment of Wounds of Diverse Etiologies: A Case Series

There is evidence in the literature that viable cryopreserved human placental membrane (vCHPM) grafts are effective in treating diabetic foot ulcers and venous leg ulcers.

OBJECTIVE

This case series presents 3 cases of chronic ulcerations - 1 arterial ulcer (AU), 1 pressure ulcer (PU), and 1 recurrence of a pyoderma gangrenosum ulcer (PGU) - that had failed previous courses of standard wound care and were subsequently treated with vCHPM to determine if the treatment is an effective modality for treating wounds of these etiologies.

MATERIALS AND METHODS

This retrospective review describes 3 cases in which patients with chronic wounds that had failed standard of care treatments for more than 4 weeks were subsequently treated with weekly applications of vCHPM. Each wound area was recorded and photographed on a weekly basis and wound area reduction also was charted weekly.

RESULTS

The PU and AU both reached full closure in 4 and 5 weeks, respectively, without complication. The patient with the PGU achieved 64% closure after 9 applications of vCHPM.

CONCLUSIONS

Viable CHPM is an effective treatment modality for wounds of diverse etiologies and shows better results than have been previously published with standard of care. In patients with PGUs, medical optimization and close management of comorbidities is essential in achieving optimal results.

[Transplantation of human placenta mesenchymal stem cells reduces the level of inflammatory factors in lung tissues of mice with acute lung injury]

Objective To investigate the influence of human placenta mesenchymal stem cells (hPMSCs) on the expression levels of inflammatory factors in the lung tissues of lipopolysaccharide (LPS)-induced acute lung injury (ALI) mice. Methods Six-week-old healthy C57BL/6 male mice were randomly divided into control group, ALI model group and hPMSC-treated group, with 8 mice in each group. LPS was trickled in ALI model group by the trachea. The hPMSC-treated mice were injected with hPMSCs by tail vein at 12 hours after administration of LPS. The control group was managed with the corresponding dose of normal saline. The surface markers of hPMSCs were identificated by flow cytometry. The mice were sacrificed after 24 hours, and the histopathological changes of lung tissues were detected by HE staining before and after injection of hPMSCs. The dry to wet mass ratio (W/D) and the myeloperoxidase (MPO) activity of the lung tissues were tested, and the levels of inflammatory factors in bronchoalveolar lavage fluid (BALF) were measured by ELISA, including tumor necrosis factor (TNF-α), interleukin-1 (IL-1) and interleukin-6 (IL-6). Results Phenotypic identification of hPMSCs showed the positive expression for CD105, CD90 and CD73, but negative expression for CD14, CD34, CD45. Compared with the control group, the pathological injury of the lung tissues was severe in the ALI model group, the W/D ratio and MPO activity in the lung tissues increased, and the levels of TNF-α, IL-1, and IL-6 in the BALF were significantly elevated. Compared with the ALI model group, the treatment with hPMSCs alleviated the lung pathological damage, decreased the W/D ratio and MPO activity in the lung tissues, and down-regulated the expressions of TNF-α, IL-1 and IL-6 in the BALF. Conclusion Treatment with hPMSCs can reduce the levels of inflammatory cytokines in the lung tissues and attenuate LPS-induced ALI.

Viable placental allograft as a biological dressing in the clinical management of full-thickness thermal occupational burns: Two case reports

RATIONALE

Occupational burn injuries can be detrimental and difficult to manage. The majority of complex cases are referred and managed at regional burn centers where access to specialized care is available. As an alternative to hospitalization with staged surgical procedures, placental products may be used for outpatient medical management of these common burn injuries, especially if access to a regional burn center is limited or restricted.Fresh amnion has been a treatment of choice in burns for more than 100 years. As a biological covering with a broad scope of potential uses, human placental membranes represent a dressing that is particularly advantageous for burn therapy. Recent advances in tissue-preservation technology have allowed for the commercialization of placental amnion products.

PATIENT CONCERNS

To address several complications associated with burn injuries-contractures, scar formation, and pain-a viable cryopreserved placental membrane (vCPM) (Grafix-PRIME, Osiris Therapeutics, Inc., MD) retaining the anti-inflammatory, anti-fibrotic, and antimicrobial properties of fresh placental tissues was chosen for clinical use in the 2 cases reported, where both patients had restricted access to the regional burn center.

DIAGNOSES

Two cases of work-related extremity burns presented to a local rural hospital for immediate post-injury assessment. The 1 case was of a man who sustained a 55.4 cm full-thickness 3 degree thermal burn with exposed bone and tendon, to the left dorsal forefoot after having an industrial pressure washer caught on his work boot. The 2 case was of a female who sustained a 4.7 cm full-thickness 3 degree crush burn to the dorsum extensor surface of her dominant hand's index finger after applying 80-pounds per square inch of heated pressure from a hydraulic press.

INTERVENTIONS

Both burn patients elected to continue their care at the outpatient-based wound and hyperbaric center, receiving a combination of weekly ad libitum debridement, applications of vCPM, and occupational therapy.

OUTCOMES

Both burns reached timely wound closure, and patients regained full range of motion of the affected limb, allowing for early return to work. The average number of allograft applications was 7.5, allowing both patients to return to work in an average of 63.5 days without adverse events or post-treatment complications.

LESSONS

The incorporation of this product in the treatment of these complex burns prevented amputation in one patient, and skin autografting and potential index finger contracture-formation in the second patient. The incorporation of vCPM in burn management may offer a new approach to outpatient burn management and may mitigate several of the complications seen post burn injury, leading to favorable patient outcomes.

The use of viable cryopreserved placental tissue in the management of a chronic rectovaginal fistula

We present a case of a chronic recurrent rectovaginal fistula that initially arose from complications of haemorrhoid surgery and had failed multiple prior surgical repairs. The fistula was successfully managed using viable cryopreserved placental tissue.

Wound Closure in Smoking Peripheral Arterial Disease Patients With Treatment-Refractory Ulcerations: A 12-Month Follow-up Case Series

Despite ongoing smoking cessation efforts and optimized perfusion, failed wound closure in the presence of peripheral arterial disease (PAD) and diabetes are common. A clinical effectiveness review was conducted in actively smoking diabetic patients diagnosed with PAD, treated with serial applications of a viable intact cryopreserved human placental membrane (vCPM) (Grafix, Osiris Therapeutics Inc, Columbia, MD) for recalcitrant lower extremity ulcerations (n = 6). More than half of the patients were not candidates for revascularization. Baseline vascular status in 5 of 6 lower-extremity wounds remained unchanged throughout the entire course of vCPM treatment. Daily cigarette consumption averaged 18 cigarettes per patient. Mean wound duration and mean surface area was 53 weeks and 4.6 cm2, respectively. Mean number of vCPM applications and time to closure was 7.0 grafts in 7.8 weeks. There were no wound-related infections or amputations and no vCPM-related adverse events. All 6 wounds remained closed at the 12-month follow-up visit. In conclusion, vCPM demonstrated clinically effective outcomes in 6 previously nonhealing ulcerations despite ongoing smoking habits in the presence of PAD and diabetes.

Immune tolerance induction using fetal directed placental injection in rodent models: a murine model

Objectives

Induction of the immune response is a major problem in replacement therapies for inherited protein deficiencies. Tolerance created in utero can facilitate postnatal treatment. In this study, we aimed to induce immune tolerance towards a foreign protein with early gestational cell transplantation into the chorionic villi under ultrasound guidance in the murine model.

Methods

Pregnant C57BL/6 (B6) mice on day 10 of gestation were anesthetized and imaged by high resolution ultrasound. Murine embryos and their placenta were positioned to get a clear view in B-mode with power mode of the labyrinth, which is the equivalent of chorionic villi in the human. Bone marrow cells (BMCs) from B6-Green Fluorescence Protein (B6GFP) transgenic mice were injected into the fetal side of the placenta which includes the labyrinth with glass microcapillary pipettes. Each fetal mouse received 2 x 10⁵ viable GFP-BMCs. After birth, we evaluated the humoral and cell-mediated immune response against GFP.

Results

Bone marrow transfer into fetal side of placenta efficiently distributed donor cells to the fetal mice. The survival rate of this procedure was 13.5%(5 out of 37). Successful engraftment of the B6-GFP donor skin grafts was observed in all recipient (5 out of 5) mice 6 weeks after birth. Induction of anti-GFP antibodies was completely inhibited. Cytotoxic immune reactivity of thymic cells against cells harboring GFP was suppressed by ELISPOT assay.

Conclusions

In this study, we utilized early gestational placental injection targeting the murine fetus, to transfer donor cells carrying a foreign protein into the fetal circulation. This approach is sufficient to induce both humoral and cell-mediated immune tolerance against the foreign protein.

Removing the vertebrate-specific TBP N terminus disrupts placental beta2m-dependent interactions with the maternal immune system

Mammalian TBP consists of a 180 amino acid core that is common to all eukaryotes, fused to a vertebrate-specific N-terminal domain. We generated mice having a modified tbp allele, tbp(DeltaN), that produces a version of TBP lacking 111 of the 135 vertebrate-specific amino acids. Most tbp(DeltaN/DeltaN) fetuses (>90%) died in midgestation from an apparent defect in the placenta. tbp(DeltaN/DeltaN) fetuses could be rescued by supplying them with a wild-type tetraploid placenta. Mutants also could be rescued by rearing them in immunocompromised mothers. In immune-competent mothers, survival of tbp(DeltaN/DeltaN) fetuses increased when fetal/placental beta2m expression was genetically disrupted. These results suggest that the TBP N terminus functions in transcriptional regulation of a placental beta2m-dependent process that favors maternal immunotolerance of pregnancy.

Amniotic membranes as prosthetic material: experimental utilization data of a rat model

BACKGROUND/PURPOSE

Prosthetic materials are applied for closing big tissue defects, the repair of traumatized organs, or hernias. Because nonabsorbable synthetic materials are rigid, possess a defined and unchangeable size, and foreign body reaction (FBR) may occur, biological materials may be an alternative.

METHODS

In experimental studies in rats the authors implanted the fetal parts of the human amniotic membranes and examined the utilization and FBR induced in a standardized model. In addition amnion (AM) was combined with vicryl-net (VN) for higher implant stability. Fifteen, 30 and 90 days after implantation, macroscopic appearance was examined, and light microscopy and immunohistology testing of the specimens were performed.

RESULTS

Adhesions to parenchymal organs and omentum were present irrespective of the side facing the abdominal cavity. AM induced a rapid FBR, which diminished with time. Chorion (CH) and parts of the AM were resorbed within the examined period after infiltration with recipient cells and neovascularisation. The combined implant, AM, and VN showed best results because disadvantages of one material could be compensated for by the advantages of the other.

CONCLUSION

The studies show that AM, in its anatomic definition, combined with VN proves to be a safe and reliable prosthetic material for the use in tissue defects.

Immunohistochemical detection of cells labeled with bromodeoxyuridine after neural transplantation

Pregnant rats were treated with 5-bromo-2'-deoxyuridine (BrdU) from embryonic d 12 (ED12) to ED14. BrdU administration allowed timed labeling of dividing embryonic cells in utero, since the drug is incorporated into the DNA in place of thymidine during the S-phase of the cell cycle. ED14 rat cerebral cortex or placenta was grafted into the brain of adult rats. Anti-bromodeoxyuridine immunohistochemistry was used for identifying labeled transplanted cells after different survival periods in paraffin-embedded sections. BrdU labeled cells were observed in both intraventricular and intraparenchymal cortical grafts, even after a 3-mo survival. Although the percentage of positive cells decreased in comparison with ED14 cortex, the level of BrdU (i.e., the intensity of anti-BrdU immunohistochemistry) in labeled nuclei was probably the same. BrdU pretreatment of ED14 cells prior to grafting did not affect the proliferative ability of the grafted tissue. In ED14 placental grafts, all trophoblastic cells were labeled distinctly. This precise labeling technique enabled an examination of individual migrating trophoblastic cells. However, migration of these cells into the host brain was very limited.

[The surgical treatment of periradicular cysts of the jaws]

The author has succeeded in improving functional results of surgical treatment of the teeth that caused pararadical cysts. This was due to access to the pathologic focus, preservation of the 'causative' tooth root, filling of the residual osseous cavity with formalin-treated allogenic placental transplant. A total of 79 patients were operated on using this method. Late results were followed up for 2 years, no recurrences occurred and functional status of the operated on 'causative' teeth permitted their use as abutment teeth for bridge dentures.

Growth of mouse ectoplacental cone cells in subcutaneous tissues. Development of placental-like cells

Ectoplacental cones of mouse embryos collected on day 8 of pregnancy were grafted into the dorsal subcutaneous tissue of host mice. The grafts were collected between days 3 and 8 after transfer and processed for light and electron microscope morphological analysis as well as for cytochemistry of nonspecific alkaline phosphatase. Fragments of normal mouse placentas collected between days 12 and 18 of pregnancy were processed similarly. About 37% of the grafts were nonhemorrhagic nodules formed by different kinds of trophoblastic cells. These cells had many morphological and cytochemical features of cells present in normal mouse placentas. Nonphagocytic giant cells, glycogen cells, as well as cells with a well-developed granular endoplasmic reticulum were similar to cells found in the placenta and were always present in the grafts. Cells showing features intermediate between the above-mentioned cells and those whose cytoplasm was poor in organelles also were found in the grafts. The latter resembled cells of layer 1 of the labyrinth of the placenta. These results suggest that trophoblastic cells of the ectoplacental cones had differentiated into placental cells following their transfer to the subcutaneous tissue.

Cyclic adenosine 3',5'-monophosphate analogues modulate rat placental cell growth and differentiation

Cyclic adenosine 3',5'-monophosphate (cAMP) has been implicated in the control of placental function. The present investigation was designed to evaluate the actions of cAMP analogues on the control of rat placental development. Two model systems were used to assess the actions of cAMP in the placenta: 1) a rat placental cell line and 2) rat labyrinth placental explants. Elevation of intracellular cAMP via treatment with cAMP analogues, 3-isobutyl-1-methylxanthine, forskolin, or cholera toxin inhibited placental cell DNA synthesis whereas treatment with an analogue to cyclic guanosine 3',5'-monophosphate was without effect. The inhibitory actions of dibutyryl cAMP on DNA synthesis were at least partially reversible and were not the result of metabolic toxicity. Dibutyryl cAMP had dramatic effects on the organization and morphology of placental cells growing in vitro and diminished the ability of the placental cells to grow following transplantation into allogeneic hosts. Differentiation-associated characteristics of rat placental cells were also affected by cAMP. cAMP analogues stimulated placental cell progesterone release and inhibited placental cell alkaline phosphatase activity. Dibutyryl cAMP had effects on placental labyrinth explants similar to its effects on the placental cell line. Dibutyryl cAMP inhibited explant outgrowth while stimulating explant release of progesterone. In summary, cAMP effectively modulates the growth and differentiation of rat placental cells in vitro.

Oral submucous fibrosis--a new treatment regimen

Successful treatment of oral submucous fibrosis with local injections of chymotrypsin, hyaluronidase, and dexamethasone is reported. In resistant cases, surgical excision of the fibrotic bands with submucosal placement of fresh human placental grafts was found to be successful.

Mouse and rat placental cell lines express abundant amounts of laminin

Placental cell lines derived from midgestation placentae of outbred mice and rats were evaluated for the expression of the extracellular matrix protein laminin. The murine cell line, which has not been previously reported, demonstrates morphological characteristics similar to those of the rat cell line. Placental cell lines grow vigorously both in vitro and when transplanted to the peritoneum of allogeneic hosts. When transplanted, placental cells form cyst-like structures (with acellular cores) suspended in the peritoneal fluid, and invade abdominal structures forming solid masses. Using immunohistology, laminin was identified within in vitro cultured cells, within cyst-like structures and their acellular cores, and as a major component of the extracellular matrix of solid masses. Laminin was also identified in the normal rat chorioallantoic placenta. Evaluation of extracts from in vitro cultured placental cells, transplanted placental cells, and the normal chorioallantoic placenta by electrophoresis and immunoblotting demonstrated that laminins were composed of two species with molecular weights of 400,000 (A-chain) and 200,000 (B-chains). Mouse and rat placental cell lines may be valuable for studying laminin biosynthesis and function in the developing placenta.

Establishment of a rat placental cell line expressing characteristics of extraembryonic membranes

A cell line was derived from midgestation chorioallantoic placental explants of the outbred Holtzman rat. The cell line was found to express characteristics of extraembryonic membranes and to grow when introduced into allogeneic hosts. Growth in allogeneic hosts was detected following intraperitoneal injection of the cells but not following subcutaneous injection. The transplanted cells grew as cystic structures free in the peritoneum and as solid masses adhered to various abdominal organs. Cystic structures had a homogeneous morphology consisting of an epithelial-like cell layer surrounding a fluid-filled sac. Solid masses had a heterogeneous morphology, containing parts resembling normal components of the extraembryonic membranes (trophoblast, parietal, and visceral yolk sacs). Biochemical analysis of the placenta-derived cell line and transplanted structures derived from the cell line indicated that the cells had the potential to produce a variety of proteins characteristic of extraembryonic tissues. Cultured cells and both types of in vivo transplants produced the basement membrane protein, laminin. Peritoneal cystic structures also contained alpha-fetoprotein mRNA and very high levels of c-fos mRNA. Solid masses demonstrated elevated alkaline phosphatase activity, a marker of trophoblast cells. Cells grown in vitro expressed elevated c-myc mRNA levels, whereas, c-myc mRNA levels were reduced in the in vivo transplants. The behavior of the cell line in vitro and following in vivo transplantation suggests it contains elements capable of differentiation toward various components of the extraembryonic membranes. The results indicate that the rat placental cell line will be valuable for future studies on the differentiation of trophoblast cells and other components of the extraembryonic membranes.

Tumors arising from injection of cultured murine placental cells into normal animals: direct evidence for placental origin of tumors of two histologic types

Long-term culture of placentas obtained from the mating of a congenic C3H male mouse carrying a unique electrophoretic variant of the X-chromosome-linked enzyme phosphoglycerate kinase (PGK-1) and a normal C3H female mouse has resulted in cell lines that have apparently undergone spontaneous malignant transformation in vitro. When injected into normal syngeneic animals, these cell lines have given rise to invasive carcinomas of two distinct histologic types, an adenocarcinoma and a poorly differentiated carcinoma. Both were demonstrated to be of placental origin by the continued presence of the allozyme coded on the paternal X-chromosome. Compared to murine tumors of other etiologies, these cell lines were characterized by a high intracellular alkaline phosphatase concentration.

Growth and function of human placenta and amnion grafted to nude mice. A preliminary communication

Normal human placenta and amnion from the 20th week of pregnancy were transplanted into nude mice. The transplants retained the histological and immunohistochemical picture of the original tissue and maintained synthesis of human chorionic gonadotropin (hCG), pregnancy-specific beta 1-glycoprotein (SP1), GnRH and placental proteins PP5, PP11 and PP12 for 5 weeks. This experimental model has a wide potential application for studies on placental protein synthesis and the hormonal influence of human placenta on other simultaneously transplanted human tissues.

Rat placental hormones: attempts for identification of rat chorionic gonadotrophin and rat placental lactogen by in vivo experiments

Rat placental extracts (rPE) were investigated in bioassays for their possible content of rat placental lactogen (rPL) and rat chorionic gonadotrophin (rCG). Luteotrophic and lactogenic activity of rPL was assessed by substitution of rats depleted of endogenous prolactin (Prl) by means of bromoergocryptine (BEC) in early pregnancy and the period of lactation, respectively. The abortifacient effect of a single dose of BEC on day 6 of pregnancy was abolished by rPE equivalent to 1 g rat placenta corresponding to 5 IU bovine Prl (NIH-P-B 2). Substitution was necessary until the evening of day 7 indicating that rPL does not take over the function of Prl before day 8. During lactation rPE reversed the lactation inhibiting effect of daily BEC treatment. In this assay rPL activity corresponded to 1.25–2.5 IU bPrl/g placenta.

In order to test for the possible existence of rCG the gonadotrophic activity of rPE was assessed in immature female mice. No gonadotrophic activity was found when rPE equivalent to 1 g rat placenta was administered, whereas equivalents of 3 mg human placenta and 12 mg rat pituitary entailed a dose-dependent response. In this system 0.12 IU human chorionic gonadotrophin (hCG), which served as standard, was the minimal dose (MD) resulting in increased uterine weight.

In addition rPE was tested in the immature female rat, where the limit of detection was found to be 0.5 IU hCG. Again no gonadotrophic activity was found in rPE. As the effects of rCG might have been restricted to its presumed target, the corpus luteum of pregnancy, rPE was also tested in pregnant rats depleted of endogenous luteinizing hormone (LH) by a single injection of anti-LH antibodies on day 10 of pregnancy. A MDof 0.5 IU hCG, which served as standard, prevented resorption of foetuses in all animals tested. rPE equivalent to 3.5 g rat placenta, rat pregnancy serum of day 18 and placental transplants could not substitute for endogenous LH.

Renal damage following transplantations of heterologous placental tissue

Immunological interrelations between placenta and kidney have become a matter of interest with regard to the pathogenesis of preeclampsia. Kidney morphology of Lewis rats was studied following repeated transplantations of heterologous or syngeneic placental tissue. In most of the heterologous placenta-recipient animals, diffuse severe glomerular lesions were found, similar to those seen in women with preeclampsia. In the strongly responding recipients, endothelial cell swelling, narrowing of capillary lumina and proliferation of mesangial matrix were observed. Patchy areas of fluorescence associated with dense IgG deposition, as well as fibrin deposits demonstrated in the affected glomeruli, were correlated with histologic changes. The use of syngeneic placenta as a transplant did not cause histological or immunohistological changes. These findings support the view that differences in histocompatibility antigens between mother and fetus may be involved in the pathogenesis of the nephropathy in preeclampsia.

The immunobiology of placentation

A review of the current theories on the nature of the placental allograft and the evolution of placentation in the presence of a cellular immune response highlights the inability of current hypotheses to explain the success of both invertebrate and vertebrate placentation. Only one theory -- "the anatomical separation of the fetus from the mother" -- appears relevant. How this separation might develop during implantation is discussed.

Treatment of hypoplastic anemia in mice with placental transplants

A genetic mutation in mice (W/Wv) causes an autosomal recessive disease characterized by hypoplastic anemia which lasts throughout life. Double-dominant W/Wv anemic mice were sublethally irradiated to facilitate repopulation of marrow with transplanted cells and were injected intravenously with suspensions of 5-10 million placental cells of 15 days gestation derived from normal, isogeneic donors. Red cell counts fell promptly after irradiation and then rose progressively over a period of weeks, reaching normal levels of the nonmutant. Mean corpuscular volume and hemoglobin electrophoresis patterns of red cells in recipient W/Wv mice resembled those of normal donor animals. The therapeutic effect lasted for the duration of the observation period, in some instances over 9 mo. W/Wv mice that were administered Hanks' solution or fetal blood, instead of placental transplants, remained anemic. Late gestation placentas (18 days) were also ineffective.

Demonstration of mammotrophic activity of the mouse placenta in organ culture and by transplantation

Mammotrophic (i.e. mammogenic and/or lactogenic) activity of mouse placentae of different stages (4–19 days of pregnancy) was examined using organ co-culture of placental explants with mammary tissue. The test mammary tissues were taken from midpregnant (11–12 days) nulliparous A/Crgl mice and cultured in a synthetic medium (Waymouth's) supplemented with insulin (5 μg/ml) and aldosterone (1 μg/ml). The responses of mammary gland to placental explants were judged histologically, and were compared with those seen after the addition of ovine prolactin (5 μg/ml). With placentae from 6- to 19-day pregnant animals, distinct mammotrophic activity was seen, with the appearance of eosinophilic secretion in the mammary alveolar lumina, whereas with 4- or 5-day-old 'placentae', no mammotrophic activity was detected. Inasmuch as growth hormone does not substitute for prolactin in mammary gland development and function in the A/Crgl mouse, it can be concluded that a prolactin-like factor is present in the mouse placenta. The influence of placentae on mammary gland was further analysed by transplantation of placental fragments to mammary fat pads. Local lobuloalveolar development was prominent in some instances in the area around the placental transplants.