Human platelet lysate (or hPL) is a substitute supplement for fetal bovine serum (FBS) in experimental and clinical cell culture. It is a turbid, light-yellow liquid that is obtained from human blood platelets after freeze/thaw cycle(s). The freeze/thaw cycle causes the platelets to lyse, releasing a large quantity of growth factors necessary for cell expansion. hPL has the highest concentration of growth factors of any serum supplements. [1] FBS-free cell culture media, e.g. with platelet lysate or chemically defined/ animal component free, are used for cell therapy or regenerative medicine. They are commercially available in GMP (good manufacturing practice)-quality which is generally basis for regulatory approval. [2]
Platelets have a life span of 5 to 9 days. Because of this, the U.S. Food and Drug Administration (FDA) expires transfuse-able platelets 5 days post-collection. Typically, hPL is produced from expired platelets that have been stored in frozen conditions no later than 7 days post-collection.
hPL is created from single or pooled donor-donated platelets isolated from whole blood or by apheresis, distributed in a standard platelet collection bag. There are some differences between hPL manufacturing protocols, but they all share the same core of being frozen at very low temperatures and thawed. This process may be repeated two or three times to cause complete platelet lysis. The resultant hPL can then undergo different manufacturing steps to achieve multiple grades of hPL.
The most common form of hPL undergoes few processing steps, producing a product made of the supernatant following the freeze/thaw process. The included clotting factors require to add heparin to the cell culture media to prevent coagulation during incubation.
Another form of hPL is one that can be used in cell culture without the need of heparin, or any anticoagulant, addition. This grade of hPL goes through further manufacturing steps to inhibit the effect the clotting factors have.
Many labs around the world are creating small amounts of hPL to suit their laboratory needs. The disadvantages of this process are: cost and consistency. When creating small batches of hPL (single or few donors pooled), the lot-to-lot consistency of the hPL becomes variable. Large-scale manufacturing by pooling many platelet donors is a necessity to mitigate the donor-to-donor variability. Consistency is a top priority for experimental designs to provide reproducible results.
Platelet lysate is commonly used for supplementation of basal media in mesenchymal stem cells culture. Prior to use, the pathogen inactivation process is recommended to prevent pathogen transmission. [3]
Human platelet lysate is available commercially through AventaCell BioMedical, Elk Bioscience, Mill Creek Life Sciences, Compass Biomedical, Inc., Sexton Biotechnologies, Macopharma SA, iBiologics, PL BioScience GmbH, Life Science Group Ltd (UK) and Trinova Biochem GmbH under the product lines UltraGRO, PLTMax, PLUS, Stemulate, Human Platelet Lysate, XcytePlus, PLSOLUTION, PLMATRIX and CRUX RUFA Media Supplements. Platelet lysate has also been produced with non-human animal material and has been made commercially available by Agulos Biotech (porcine) and Japan Biomedical (bovine). Some companies provide different grades of platelet lysate including GMP versions and clinical grade for use in human clinical trials. Platelet lysate offers a true human-based recombinant protein platform. Platelet lysate has been tested in various cell culture applications including use in advanced bioreactor systems. [4]
In multicellular organisms, stem cells are undifferentiated or partially differentiated cells that can change into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type of cell in a cell lineage. They are found in both embryonic and adult organisms, but they have slightly different properties in each. They are usually distinguished from progenitor cells, which cannot divide indefinitely, and precursor or blast cells, which are usually committed to differentiating into one cell type.
Serum is the fluid and solvent component of blood which does not play a role in clotting. It may be defined as blood plasma without the clotting factors, or as blood with all cells and clotting factors removed. Serum contains all proteins except clotting factors, including all electrolytes, antibodies, antigens, hormones; and any exogenous substances. Serum also does not contain all the formed elements of blood, which include blood cells, white blood cells, red blood cells (erythrocytes), and platelets.
Apheresis is a medical technology in which the blood of a person is passed through an apparatus that separates out one particular constituent and returns the remainder to the circulation. It is thus an extracorporeal therapy.
Embryonic stem cells (ESCs) are pluripotent stem cells derived from the inner cell mass of a blastocyst, an early-stage pre-implantation embryo. Human embryos reach the blastocyst stage 4–5 days post fertilization, at which time they consist of 50–150 cells. Isolating the inner cell mass (embryoblast) using immunosurgery results in destruction of the blastocyst, a process which raises ethical issues, including whether or not embryos at the pre-implantation stage have the same moral considerations as embryos in the post-implantation stage of development.
Cell culture or tissue culture is the process by which cells are grown under controlled conditions, generally outside of their natural environment. After cells of interest have been isolated from living tissue, they can subsequently be maintained under carefully controlled conditions. They need to be kept at body temperature (37 °C) in an incubator. These conditions vary for each cell type, but generally consist of a suitable vessel with a substrate or rich medium that supplies the essential nutrients (amino acids, carbohydrates, vitamins, minerals), growth factors, hormones, and gases (CO2, O2), and regulates the physio-chemical environment (pH buffer, osmotic pressure, temperature). Most cells require a surface or an artificial substrate to form an adherent culture as a monolayer (one single-cell thick), whereas others can be grown free floating in a medium as a suspension culture. This is typically facilitated via use of a liquid, semi-solid, or solid growth medium, such as broth or agar. Tissue culture commonly refers to the culture of animal cells and tissues, with the more specific term plant tissue culture being used for plants. The lifespan of most cells is genetically determined, but some cell-culturing cells have been 'transformed' into immortal cells which will reproduce indefinitely if the optimal conditions are provided.
Wharton's jelly is a gelatinous substance within the umbilical cord, largely made up of mucopolysaccharides. It acts as a mucous connective tissue containing some fibroblasts and macrophages, and is derived from extra-embryonic mesoderm of the connecting stalk.
Cell therapy is a therapy in which viable cells are injected, grafted or implanted into a patient in order to effectuate a medicinal effect, for example, by transplanting T-cells capable of fighting cancer cells via cell-mediated immunity in the course of immunotherapy, or grafting stem cells to regenerate diseased tissues.
Fetal bovine serum (FBS) is derived from the blood drawn from a bovine fetus via a closed system of collection at the slaughterhouse. Fetal bovine serum is the most widely used serum-supplement for the in vitro cell culture of eukaryotic cells. This is due to it having a very low level of antibodies and containing more growth factors, allowing for versatility in many different cell culture applications.
A bioprocess is a specific process that uses complete living cells or their components to obtain desired products.
The epithelial–mesenchymal transition (EMT) is a process by which epithelial cells lose their cell polarity and cell–cell adhesion, and gain migratory and invasive properties to become mesenchymal stem cells; these are multipotent stromal cells that can differentiate into a variety of cell types. EMT is essential for numerous developmental processes including mesoderm formation and neural tube formation. EMT has also been shown to occur in wound healing, in organ fibrosis and in the initiation of metastasis in cancer progression.
Stem-cell therapy uses stem cells to treat or prevent a disease or condition. As of 2024, the only FDA-approved therapy using stem cells is hematopoietic stem cell transplantation. This usually takes the form of a bone marrow or peripheral blood stem cell transplantation, but the cells can also be derived from umbilical cord blood. Research is underway to develop various sources for stem cells as well as to apply stem-cell treatments for neurodegenerative diseases and conditions such as diabetes and heart disease.
Limulus amebocyte lysate (LAL) is an aqueous extract of motile blood cells (amebocytes) from the Atlantic horseshoe crab Limulus polyphemus. LAL reacts with bacterial endotoxins such as lipopolysaccharides (LPS), which are components of the bacterial capsule, the outermost membrane of cell envelope of gram-negative bacteria. This reaction is the basis of the LAL test, which is widely used for the detection and quantification of bacterial endotoxins.
Cardiomyoplasty is a surgical procedure in which healthy muscle from another part of the body is wrapped around the heart to provide support for the failing heart. Most often the latissimus dorsi muscle is used for this purpose. A special pacemaker is implanted to make the skeletal muscle contract. If cardiomyoplasty is successful and increased cardiac output is achieved, it usually acts as a bridging therapy, giving time for damaged myocardium to be treated in other ways, such as remodeling by cellular therapies.
Mesenchymal stem cells (MSCs) are multipotent cells found in multiple human adult tissues, including bone marrow, synovial tissues, and adipose tissues. Since they are derived from the mesoderm, they have been shown to differentiate into bone, cartilage, muscle, and adipose tissue. MSCs from embryonic sources have shown promise scientifically while creating significant controversy. As a result, many researchers have focused on adult stem cells, or stem cells isolated from adult humans that can be transplanted into damaged tissue.
Semen cryopreservation is a procedure to preserve sperm cells. Semen can be used successfully indefinitely after cryopreservation. It can be used for sperm donation where the recipient wants the treatment in a different time or place, or as a means of preserving fertility for men undergoing vasectomy or treatments that may compromise their fertility, such as chemotherapy, radiation therapy or surgery. It is also often used by trans women prior to medically transitioning in ways that affect fertility, such as feminizing hormone therapy and orchiectomies.
Mesenchymal stem cells (MSCs) also known as mesenchymal stromal cells or medicinal signaling cells, are multipotent stromal cells that can differentiate into a variety of cell types, including osteoblasts, chondrocytes, myocytes and adipocytes.
Adult mesenchymal stem cells are being used by researchers in the fields of regenerative medicine and tissue engineering to artificially reconstruct human tissue which has been previously damaged. Mesenchymal stem cells are able to differentiate, or mature from a less specialized cell to a more specialized cell type, to replace damaged tissues in various organs.
A cell bank is a facility that stores cells of specific genome for the purpose of future use in a product or medicinal needs, but can also describe the entity of stored cells itself. Cell banks often contain expansive amounts of base cell material that can be utilized for various projects. Cell banks can be used to generate detailed characterizations of cell lines and can also help mitigate cross-contamination of a cell line. Utilizing cell banks also reduces the cost of cell culture processes, providing a cost-efficient alternative to keeping cells in culture constantly. Cell banks are commonly used within fields including stem cell research and pharmaceuticals, with cryopreservation being the traditional method of keeping cellular material intact. Cell banks also effectively reduce the frequency of a cell sample diversifying from natural cell divisions over time.
United States of America v. Regenerative Sciences, LLC, 741 F.3d 1314, was a decision in the United States Court of Appeals for the District of Columbia Circuit filed on February 4, 2014 concerning more than minimally manipulated cell therapies and whether they are considered part of medical practice or a drug, the latter subjecting it to regulation under the Food and Drug Administration (FDA). Regenerative Sciences LLC marketed a therapy procedure called Regenexx-C for the treatment of arthritis and orthopedic injury that involved extraction and culture of mesenchymal stem cells from the same patient which were later reinjected. In 2008, The FDA notified Regenerative Sciences LLC that the procedure may not be in compliance with their regulation using an Untitled Letter, which began a series of suits and counter suits, leading to the 2014 decision upholding the FDA’s regulation of more than minimally manipulated stem cell therapies.
CellResearch Corporation is a biotechnology company with a primary focus on skin cell and cord lining stem cell research. CellResearch has one of the world's largest private skin-, scar-, and keloid-cell libraries which have been used for research by cell culture laboratories worldwide, including those at Harvard University, Procter & Gamble and Johnson & Johnson. It owns 39 patents worldwide with intellectual property for the isolation of stem cells from the umbilical cord lining membrane of all mammals, which also includes the banking and cultivation of these cells, as well as the therapeutic applications of these cells.