Grafts In Animal Models Research Articles

Unleashing innovation: 3D-printed biomaterials in bone tissue engineering for repairing femur and tibial defects in animal models - a systematic review and meta-analysis.

3D-printed scaffolds have emerged as an alternative for addressing the current limitations encountered in bone reconstruction. This study aimed to systematically review the feasibility of using 3D bio-printed scaffolds as a material for bone grafting in animal models, focusing on femoral and tibial defects. The primary objective of this study was to evaluate the efficacy, safety, and overall impact of these scaffolds on bone regeneration. Electronic databases were searched using specific search terms from January 2013 to October 2023, and 37 relevant studies were finally included and reviewed. We documented the type of scaffold generated using the 3D printed techniques, detailing its characterization and rheological properties including porosity, compressive strength, shrinkage, elastic modulus, and other relevant factors. Before incorporating them into the meta-analysis, an additional inclusion criterion was applied where the regenerated bone area (BA), bone volume (BV), bone volume per total volume (BV/TV), trabecular thickness (Tb. Th.), trabecular number (Tb. N.), and trabecular separation (Tb. S.) were collected and analyzed statistically. 3D bio-printed ceramic-based composite scaffolds exhibited the highest capacity for bone tissue regeneration (BTR) regarding BV/TV of femoral and tibial defects of animal models. The ideal structure of the printed scaffolds displayed optimal results with a total porosity >50% with a pore size ranging between 300- and 400µM. Moreover, integrating additional features and engineered macro-channels within these scaffolds notably enhanced BTR capacity, especially observed at extended time points. In conclusion, 3D-printed composite scaffolds have shown promise as an alternative for addressing bone defects.

Cepharanthine triggers ferroptosis through inhibition of NRF2 for robust ER stress against lung cancer

BackgroundSevere endoplasmic reticulum (ER) stress elicits apoptosis to suppress lung cancer. Our previous research identified that Cepharanthine (CEP), a kind of phytomedicine, possessed powerful anti-cancer efficacy, for which the underlying mechanism was still uncovered. Herein, we investigated how CEP induced ER stress and worked against lung cancer. MethodsThe differential expression genes (DEGs) and enrichment were detected by RNA-sequence. The affinity of CEP and NRF2 was analyzed by cellular thermal shift assay (CETSA) and molecular docking. The function assay of lung cancer cells was measured by western blots, flow cytometry, immunofluorescence staining, and ferroptosis inhibitors. ResultsCEP treatment enriched DEGs in ferroptosis and ER stress. Further analysis demonstrated the target was NRF2. In vitro and in vivo experiments showed that CEP induced obvious ferroptosis, as characterized by the elevated iron ions, ROS, COX-2 expression, down-regulation of GPX4, and atrophic mitochondria. Moreover, enhanced Grp78, CHOP expression, β-amyloid mass, and disappearing parallel stacked structures of ER were observed in CEP group, suggesting ER stress was aroused. CEP exhibited excellent anti-lung cancer efficacy, as evidenced by the increased apoptosis, reduced proliferation, diminished cell stemness, and prominent inhibition of tumor grafts in animal models. Furthermore, the addition of ferroptosis inhibitors weakened CEP-induced ER stress and apoptosis. ConclusionIn summary, our findings proved CEP drives ferroptosis through inhibition of NRF2 for induction of robust ER stress, thereby leading to apoptosis and attenuated stemness of lung cancer cells. The current work presents a novel mechanism for the anti-tumor efficacy of the natural compound CEP.

Ex Vivo Liver Machine Perfusion: Comprehensive Review of Common Animal Models.

The most common preservation technique for liver grafts is static cold storage. Due to the organ shortage for liver transplantation (LT), extended criteria donor (ECD) allografts are increasingly used-despite the higher risk of inferior outcome after transplantation. Ex vivo liver machine perfusion (MP) has been developed to improve the outcome of transplantation, especially with ECD grafts, and is currently under evaluation in clinical trials. We performed a literature search on PubMed and ISI Web of Science to assemble an overview of rodent and porcine animal models of ex vivo liver MP for transplantation, which is essential for the present and future development of clinical liver MP. Hypothermic, subnormothermic, and normothermic MP systems have been successfully used for rat and pig LT. In comparison with hypothermic systems, normothermic perfusion often incorporates a dialysis unit. Moreover, it enables metabolic assessment of liver grafts. Allografts experiencing warm ischemic time have a superior survival rate after MP compared with cold storage alone, irrespective of the temperature used for perfusion. Furthermore, ex vivo MP improves the outcome of regular and ECD liver grafts in animal models. Small and large animal models of ex vivo liver MP are available to foster the further development of this new technology. Impact Statement Ex vivo machine perfusion is an important part of current research in the field of liver transplantation. While evidence for improve storage is constantly rising, the development of future applications such as quality assessment and therapeutic interventions necessitates robust animal models. This review is intended to provide an overview of this technology in common large and small animal models and to give an outlook on future applications. Moreover, we describe developmental steps that can be followed by others, and which can help to decrease the number of animals used for experiments based on the replace, reduce, refine concept.

Better Outcomes with Intranigral versus Intrastriatal Cell Transplantation: Relevance for Parkinson's Disease.

Intrastriatal embryonic ventral mesencephalon grafts have been shown to integrate, survive, and reinnervate the host striatum in clinical settings and in animal models of Parkinson’s disease. However, this ectopic location does not restore the physiological loops of the nigrostriatal pathway and promotes only moderate behavioral benefits. Here, we performed a direct comparison of the potential benefits of intranigral versus intrastriatal grafts in animal models of Parkinson’s disease. We report that intranigral grafts promoted better survival of dopaminergic neurons and that only intranigral grafts induced recovery of fine motor skills and normalized cortico-striatal responses. The increase in the number of toxic activated glial cells in host tissue surrounding the intrastriatal graft, as well as within the graft, may be one of the causes of the increased cell death observed in the intrastriatal graft. Homotopic localization of the graft and the subsequent physiological cell rewiring of the basal ganglia may be a key factor in successful and beneficial cell transplantation procedures.

Effects of the different-sized external stents on vein graft intimal hyperplasia and inflammation.

The poor long-term patency ratio of vein grafts prevents patients from benefiting from coronary artery bypass graft (CABG). It is reported that external venous stents have notably improved the patency ratio of stented vein grafts in animal models. The most crucial influence on stented grafts' fate is the size of the stents. This study aims to investigate the effects on intimal hyperplasia and inflammation of vein graft by using different sizes of stents and explore the potential mechanism. Two different sizes of external stents were fabricated through 3D printing technology. Male SD rats were divided into three groups. In the control group rat's autologous left jugular vein was grafted on the ipsilateral artery directly. In the stent groups, grafts were surrounded by two different-sized stents before anastomosing with arteries. The patency ratio and diameter of the grafts were examined by ultrasound. Masson staining was used to characterize intimal hyperplasia. The expression of inflammatory factors was detected by immunohistochemical staining. Moreover, TUNEL staining was used to label apoptotic cells. The two sizes of external stents were fabricated by 3D printing technology. In the control group, the intima area and wall thickness dramatically increased 8 weeks after implantation. While in the stent groups, these data only slightly increased, especially in the 1.5 mm-stent group. The expressions of inflammatory factors in TNF signaling were more remarkable than in the control group. On the contrary, the expressions were rarely detected in the stent groups. Similarly, the number of TUNEL positive cells dramatically decreased by using the appropriate-sized stent. In this study, we concluded that the appropriate sizes of external stents could effectively inhibit vein graft neointima formation, attenuate inflammatory reaction and reduce cell apoptosis, which might improve the long-term patency ratio of vein grafts.

Effect of Platelet-Rich Fibrin on Fat Grafting in Animal Models: A Meta-Analysis.

Autologous fat grafting has been widely used in plastic and reconstructive surgery, but one of the main reasons for limiting its application is the high resorption rate. Platelet-rich fibrin (PRF) is a new generation of platelet concentrate that has recently been used to improve the survival rate of fat grafts. The purpose of this study was to evaluate the effect of PRF on fat grafting. Animal studies in four databases (PubMed, Cochrane library, Ovid, and Wan fang database) were searched up to July 2019. A meta-analysis was performed to compare PRF + fat grafting and fat grafting alone or platelet-rich plasma (PRP) + fat grafting in animal models. Six studies with 83 animals (123 fat graftings) were included in our meta-analysis. The fat survival rate (mean difference (MD) 0.14, P<0.00001) and the microvessel density (MVD) (standardized mean difference 4.20, P = 0.02) of the PRF + fat group were significantly higher than that of the fat alone group. There was no significant difference between the PRF + fat group and PRP + fat group in the fat survival rate (MD 0.05, P = 0.06). This study found that PRF combined with fat grafting may have an effect on improving the survival rate and MVD of fat grafts. However, when comparing the effects of PRF and PRP on the fat survival rate, there is currently no clear evidence to prove the difference between them. More preclinical and clinical studies are necessary to further clarify the effect of PRF on fat grafting in humans. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Improving Surgical Methods for Studying Vascular Grafts in Animal Models.

While clinical vascular grafting uses an end-to-side surgical method, researchers primarily use end-to-end implant techniques in preclinical models. This may be due in part to the limitations of using small animal models in research. The work presented here provides support and evidence for the improvement of vascular graft implant techniques by demonstrating the successful implantation of experimental grafts into both large and small animal models. Specifically, models of aortoiliac baboon (Papio anubis) bypass and common carotid rabbit (Oryctolagus cuniculus) bypass were used to test vascular grafts for thrombosis and vascular healing after 1 month using an end-to-side anastomosis grafting procedure. Patency was evaluated with ultrasound or histological techniques, and neointimal growth was quantified with histology. In the development of this procedure for small animals, both an end-to-end/end-to-side and an end-to-side/end-to-side configuration were tested in rabbits. One hundred percent of rabbit implants (2/2) with an end-to-end/end-to-side configuration were patent at explant. However, with the end-to-side/end-to-side configuration, 66% (6/9) of rabbit implants and 93% (13/14) of baboon implants remained patent at 1 month, suggesting the importance of replicating the end-to-side method for testing vascular grafts for clinical use. This study describes feasible preclinical surgical procedures, which simulate clinical vascular bypass grafts even in small animals. Widespread implementation of these end-to-side surgical techniques in these or other animals should improve the quality of experimental, preclinical testing and ultimately increase the likelihood of translating new vascular graft technologies into clinical applications.

Establishment of a rat and guinea pig aortic interposition graft model reveals model-specific patterns of intimal hyperplasia

Although the aortic interposition bypass model has been widely used to evaluate biomaterials for bypass grafting, there is no comprehensive description of the procedure or of the distribution of intimal hyperplasia that results. The objectives of this study were to (1) review and summarize approaches of aortic interposition grafting in animal models, (2) determine the pertinent anatomy for this procedure, (3) validate this model in the rat and guinea pig, and (4) compare the distribution of intimal hyperplasia that develops in each species. A literature search was performed in PubMed from 1980 to the present to analyze the use of anesthesia, anticoagulation, antiplatelet agents, graft material, suture, and anastomotic techniques. Using 10-week-old male Sprague-Dawley rats and Hartley guinea pigs, we established pertinent aortic anatomy, developed comparable models, and assessed complications for each model. At 30days, the graft and associated aorta were explanted, intimal formation was assessed morphometrically, and cellularity was assessed via nuclear counting. We reviewed 30 articles and summarized the pertinent procedural findings. Upon establishing both animal models, key anatomic differences between the species that affect this model were noted. Guinea pigs have a much larger cecum, increased retroperitoneal fat, and lack the iliolumbar vessels compared with the rat. Surgical outcomes for the rat model included a 53% technical success rate and a 32% technical error rate. Surgical outcomes for the guinea pig model included a 69% technical success rate and a 31% technical error rate. These two species demonstrated unique distribution of intimal hyperplasia at 30days. Intimal hyperplasia in the rat model was greatest at two areas, the proximal graft (5400 μm2; P< .001) and distal graft (2800 μm2; P< .04), whereas the guinea pig model developed similar intimal hyperplasia throughout the graft (4500-5100 μm2; P< .01). In this report, we summarize the literature on the aortic interposition graft model, present a detailed description of the anatomy and aortic interposition graft procedure in the rat and guinea pig, and describe a unique distribution of intimal formation that results in both species. This information will be helpful when designing studies to evaluate novel graft materials in the future.

Symptomatic ischemia resulting from late upper extremity venous graft occlusion

Summary Reconstruction of traumatic or occluded vessels with vein grafts to treat ischemia of the hand is common in current upper-extremity surgery. Late symptomatic occlusion of the venous graft, however, has seldom been reported. We report two cases involving patients who developed acute symptomatic ischemia in their hands from occlusion of their vein grafts > 15 years after their initial surgery. Our management strategy was additional arterial reconstruction. An extensive review of the literature on late vein graft occlusion in the upper extremity was performed to compare presentations, management strategies, and outcomes for this disease. In both cases, computed tomography angiogram results confirmed clinical suspicions of late venous graft occlusions. Conservative management was attempted first with no resolution of symptoms. Repeated arterial or venous grafting was performed to bypass the diseased segments. PubMed searches with the separate key phrases “late graft occlusion”, “late vein graft occlusion”, and “late vein graft occlusion hand” were entered. Titles and abstracts were filtered and relevant full texts were reviewed. Limited studies have been reported on symptomatic late vein graft occlusions of the upper extremity. Experimental studies have shown that intra-arterial microvenous grafts undergo the same vessel remodeling as macrovenous grafts in animal models. The same mechanism of neointima proliferation and subsequent atherosclerotic events were considered the main causes of graft occlusions in these cases. After regrafting, their symptoms subsided during follow-ups at 1 year and 6 years, respectively. We present two rare clinical case reports of patients who suffered ischemic symptoms in their hands from late (> 15 years) occlusion of vein grafts. Both patients were assessed with preoperative computed tomography angiograms and successfully treated with regrafting. In cases of late occlusion with ischemic symptoms, a repeat arterial reconstruction with venous or arterial grafting is recommended.

Translating stem cell research to the clinic: A constant crosstalk between basic and applied research

AbstractPluripotent stem cells hold great promise for the generation of patient-specific cells for disease modeling and regenerative medicine. Focusing on a recent study reporting the successful generation of midbrain dopaminergic neurons and their efficient grafting in animal models of Parkinson’s disease, I discuss how crosstalk between basic and applied stem cell research more generally paves the road toward clinical translation.

Genetically Engineered Islets and Alternative Sources of Insulin-Producing Cells for Treating Autoimmune Diabetes: Quo Vadis?

Islet transplantation is a promising therapy for patients with type 1 diabetes that can provide moment-to-moment metabolic control of glucose and allow them to achieve insulin independence. However, two major problems need to be overcome: (1) detrimental immune responses, including inflammation induced by the islet isolation/transplantation procedure, recurrence autoimmunity, and allorejection, can cause graft loss and (2) inadequate numbers of organ donors. Several gene therapy approaches and pharmaceutical treatments have been demonstrated to prolong the survival of pancreatic islet grafts in animal models; however, the clinical applications need to be investigated further. In addition, for an alternative source of pancreatic β-cell replacement therapy, the ex vivo generation of insulin-secreting cells from diverse origins of stem/progenitor cells has become an attractive option in regenerative medicine. This paper focuses on the genetic manipulation of islets during transplantation therapy and summarizes current strategies to obtain functional insulin-secreting cells from stem/progenitor cells.

Effect of neuronal precursor cells derived from medial ganglionic eminence in an acute epileptic seizure model

Most of the gamma-aminobutyric acid (GABA)ergic interneurons in the cerebral cortex originate from restricted regions of the ventral telencephalon known as the caudal and medial ganglionic eminence (MGE) and from the preoptic area. It is well established that dysfunction of GABAergic interneurons can lead to epilepsy. During the last decade new approaches to prevent, reduce, or reverse the epileptic condition have been studied, including cell-based therapy from different sources. Recent studies have shown that transplanted neuronal precursor cells derived from MGE have the ability to migrate, differentiate into inhibitory GABAergic interneurons, and integrate into cortical and hippocampal networks, modifying the inhibitory tone in the host brain. Therefore, transplantation of neuronal precursors derived from MGE into the postnatal central nervous system (CNS) could modify the neuronal circuitry in neurologic diseases in which inhibitory synaptic function is altered, such as in epilepsy. Here, we evaluated the seizure susceptibility of mice transplanted with MGE-derived cells in the maximum electroconvulsive shock (MES) model and we review some data from different studies using GABAergic precursor or GABA-releasing cell grafts in animal models of seizure and epilepsy.

Ex vivo infection of human embryonic spinal cord neurons prior to transplantation into adult mouse cord

BackgroundGenetically modified pseudorabies virus (Prv) proved suitable for the delivery of foreign genes to rodent embryonic neurons ex vivo and maintaining foreign gene expression after transplantation into spinal cord in our earlier study. The question arose of whether human embryonic neurons, which are known to be more resistant to Prv, could also be infected with a mutant Prv. Specifically, we investigated whether a mutant Prv with deleted ribonucleotide reductase and early protein 0 genes has the potential to deliver marker genes (gfp and β-gal) into human embryonic spinal cord neurons and whether the infected neurons maintain expression after transplantation into adult mouse cord.ResultsThe results revealed that the mutant Prv effectively infected human embryonic spinal cord neurons ex vivo and the grafted cells exhibited reporter gene expression for several weeks. Grafting of infected human embryonic cells into the spinal cord of immunodeficient (rnu-/rnu-) mice resulted in the infection of some of the host neurons.DiscussionThese results suggest that Prv is suitable for the delivery of foreign genes into transplantable human cells. This delivery method may offer a new approach to use genetically modified cells for grafting in animal models where spinal cord neuronal loss or axon degeneration occurs.

Skin and oral mucosa equivalents: construction and performance

The skin and the oral mucosa act as a barrier against the external environment. Loss of this barrier function causes dehydration and a high risk of infection. For the treatment of extensive skin wounds such as in severe burns, autologous skin for transplantation is often not available in sufficient amounts. Reconstructions in the oral cavity, as required after tumor resections or cleft palate repair, are often complicated by similar problems. In the last two decades, the field of tissue engineering has provided new solutions to these problems. Techniques have been developed for the culture of epithelial grafts, dermal substitutes, and the combination of these two to a 'functional' skin or mucosa equivalent. The present review focuses on developments in the field of tissue engineering of skin and oral mucosa. The performance of different types of engineered grafts in animal models and clinical studies is discussed. Recent developments such as the use of epithelial stem cells, and gene therapy with transduced skin grafts are also discussed.

Adult stem cell therapies for neurological disorders: Benefits beyond neuronal replacement?

The modest capacity of endogenous repair processes in the central nervous system (CNS) justifies the broad interest in the development of effective stem cell based therapies for neurodegenerative disorders and other acute or chronic lesions. Motivated by the ambitious expectation to achieve functional neuronal replacement, several studies have already evidenced a potential benefit of stem cell grafts in animal models of human disorders. Nevertheless, growing evidence suggests that the effects orchestrated by stem cells, in most experimental cases, are not necessarily associated with the generation of new neurons. This hypothesis correlates with the versatile properties of adult and embryonic stem cells. When introduced into the lesioned CNS, nondifferentiated stem cells can have a positive influence through intrinsic neuroprotective capacities related to the production of neurotrophic factors, stimulation of endogenous neurogenesis, and modulation of neuroinflammation. Stem cells are also endowed with a multipotent differentiation profile, suggesting that a positive outcome could result from the replacement of nonneuronal cell types, in particular astrocytes and oligodendrocytes. Focusing on adult stem cells, this Review aims at summarizing experimental observations supporting the concept that, in cell-based therapies, stem cells operate not through a unidirectional mechanism (e.g., generating neurons) but rather as cellular mediators of a multitude of biological activities that could provide a favorable outcome for diverse nervous disorders.

Human stem cell grafts as therapies for motor neuron disease

Stem cell transplantation, a widely accepted therapeutic approach to diseases of modular organs such as the heart and the endocrine pancreas, remains a controversial option for the nervous system. However, historical advances in the 1990s on key aspects of neural plasticity and the appreciation of the selective vulnerability of nerve cells and systems in degenerative and traumatic diseases require a re-examination of this scepticism. The successes and failures with prior trophic factor therapies are particularly enlightening; many lessons from this era can be creatively absorbed as the early outcomes with stem cell grafts in animal models of disease are evaluated. Stem cell grafting into spinal cord, traditionally a doomed enterprise because of lack of neurogenicity in this region and multiple early failures, is becoming promising again with recent findings from the authors' laboratory and elsewhere that specific types of cells and methods of culture are associated with much improved biological and functional outcomes.

Factor Xa inhibition by immobilized recombinant tissue factor pathway inhibitor

The recombinant form of the endogenous anticoagulant, tissue factor pathway inhibitor (rTFPI), is a potent inhibitor of Factor Xa (FXa) and the tissue factor–factor VIIa (TF:VIIa) complex. Surface-immobilized rTFPI reduces the thrombogenicity and intimal hyperplasia associated with synthetic vascular grafts in animal models and specifically reduces fibrin deposition on collagen-impregnated Dacron grafts from native blood in an in vitro flow model. The FXa inhibitory capacity of rTFPI in the bulk phase has been demonstrated in static systems and immobilized rTFPI reduces fibrin deposition in whole blood in vitro and animal studies; however, the specific mode of this anticoagulation has not been studied. Therefore, a comparison was made between the FXa binding capacity of two forms of immobilized rTFPI, i.e., passively adsorbed and covalently bound. The rTFPI-coated surfaces were evaluated using a parallel-plate flow reactor and comparing the amount of FXa exiting the flow chamber after exposure to an rTFPI-coated versus an uncoated plate. The results demonstrate that adsorbed rTFPI exhibits increased binding capacity (1.5–3.6 times) the expected stoichiometry via interactions with the C-terminus, whereas covalently-bound rTFPI interacts with FXa in a 1:1 stoichiometry. Thus, the results imply that specific FXa inhibition is a key component of the anticoagulant effect of rTFPI-coated surfaces and that passive adsorption of rTFPI to glass surfaces produces a more effective coating than covalent binding of rTFPI.

Intimal Exuberance: Veins in Jeopardy

Address reprint requests to Anupam Agarwal, M.D., Associate Professor of Medicine, Biochemistry and Molecular Biology, Box 100224, University of Florida, 1600 SW Archer Road, Gainesville, FL 32610. E-mail: .ude.lfu.cdren.psren@lawraga

Cell replacement therapy in human neurodegenerative disorders

Clinical studies with intrastriatal transplants of embryonic mesencephalic tissue in patients with Parkinson's disease (PD) provide proof-of-principle for the cell replacement strategy in the diseased human brain. The grafted dopaminergic neurons can reinnervate the denervated striatum, restore regulated dopamine release and movement-related frontal cortical activation, and give rise to significant symptomatic relief. In the most successful cases, patients have been able to withdraw l-DOPA treatment after transplantation and resume an independent life. However, it is unlikely that transplantation of human primary embryonic tissue can be developed into therapies for large numbers of patients. Stem cells could be useful as an unlimited source of specific neuron types, e.g. dopamine neurons. So far, neurons with at least some dopaminergic characteristics have been generated from stem cells. However, their survival after grafting in animal models has been poor and it is also unclear if they function as normal dopamine neurons. It is important to emphasize that the biological problems which have to be solved in order to develop stem cell-based therapies for neurodegenerative disorders like PD are complex and should not be underestimated. Progress should therefore be made with great care.

A multiple target neural transplantation strategy for Parkinson's disease.

Intracerebral transplantation of embryonic ventral mesencephalic tissue is a potential treatment for patients with Parkinson's disease for whom medical management is unsatisfactory. Neural transplantation for parkinsonism has been studied experimentally in animal models of Parkinson's disease for more than two decades. These animal studies have shown significant graft survival, synapse formation, graft induced-dopamine release, and behavioural recovery in transplanted animals. Encouraged by these results, clinical programs have been initiated over the past 15 years; more than 250 patients worldwide have undergone neural transplantation. Both animal and clinical studies indicate that neural transplantation has the potential to become a valuable treatment option for Parkinson's disease. However, while many transplant recipients obtain clinically useful symptom relief, in all cases functional recovery is incomplete. Certain symptoms do not respond well to transplant therapy, and those symptoms that do typically do not resolve completely. This has spurred efforts to optimize the transplant procedure. One important approach is exploring novel methods such as multiple site transplantation. This transplantation strategy results in a more complete reinnervation of the dopaminergic circuitry that is affected in Parkinson's disease. In principle, multiple site transplantation should provide a more satisfactory resolution of symptoms. Here we review the progress made in multiple site neural transplantation for Parkinson's disease. The effects of intrastriatal, intranigral, intrasubthalamic nucleus, and intrapallidal grafts in animal models of Parkinson's disease are analysed. The current data suggest that intrastriatal grafts alone are inadequate to promote complete functional recovery. A multiple target strategy may restore dopaminergic input to affected basal ganglia nuclei and improve outcomes of neural transplantation in Parkinson's disease.