Question

Which is not a complication for an autograft (from one to oneself) transplant of adult stem cells? a. Limited plasticity of adult stem cells hinders the use of non-neuronal stem cells b. After in vitro culture and transplantation, the immune system recognizes the transplanted cells as foreign and are rejected c. Adult stem cells grown in vitro are usually unable to proliferate in an unspecialized state d. In vitro conditions that allow for adequate proliferation of adult stem cells fail to direct the differentiation to functionally useful cells

Short answer

a. The limited plasticity of adult stem cells b. Immune system rejection of transplanted cells c. Maintaining unspecialized state in vitro d. Directing differentiation to desired cell types Answer: b. Immune system rejection of transplanted cells

Step-by-step solution

: Adult stem cells are multipotent, which means they have limited plasticity and may not differentiate into all cell types. In vitro culture conditions are important for proliferation and differentiation. Transplanted cells can potentially be recognized as foreign and rejected by the immune system in certain transplant scenarios. In autograft transplants, however, the patient's own cells are used, so there is generally no immune system rejection. #tag_step_2#: Identify the answer choice that is not a complication for autograft transplants

: The answer choice that does not describe a complication for autograft transplants is (b). In autograft transplants, the patient's own cells are used, so there should be no immune system rejection as they are not recognized as foreign. The other answer choices are complications that can arise with adult stem cell transplants in general-- issues with limited plasticity (a), difficulties maintaining an unspecialized state in vitro (c), and problems directing differentiation to useful cells (d). So, the correct answer is: b. After in vitro culture and transplantation, the immune system recognizes the transplanted cells as foreign and are rejected.

Key concepts

Stem Cell Plasticity

The term 'stem cell plasticity' refers to the ability of stem cells to differentiate into various cell types. Adult stem cells, such as those found in bone marrow, are multipotent. This means they have a more limited range of differentiation compared to pluripotent stem cells, like embryonic stem cells, which can develop into almost all cell types.

Adult stem cells typically differentiate into cell types of their tissue of origin. For example, hematopoietic stem cells in bone marrow will usually become various kinds of blood cells. The limited plasticity of adult stem cells is sometimes a hurdle for regenerative medicine, because it restricts the types of tissues that can be repaired using these cells. However, recent research aims to enhance the plasticity of adult stem cells using various techniques, so they might be applied more broadly in medical treatments.

Immune Rejection in Transplants

Transplant rejection occurs when the immune system recognizes transplanted tissue as foreign and attacks it. This is a major challenge in allografts, where tissues are transplanted from a donor to a recipient who is not an identical genetic match.In the context of stem cell transplants, using the patient's own cells, known as an autograft, generally does not lead to immune rejection. The immune system recognizes these cells as part of the self, thus preventing the rejection response. However, in the case of allografts or xenografts (where the cells come from a donor of another species), immune rejection is a significant concern. To lessen the risk, patients may be given immunosuppressive drugs, although these can have their own set of complications, including a heightened susceptibility to infections.

In Vitro Proliferation and Differentiation

When scientists culture stem cells in a laboratory, they aim for the cells to proliferate, meaning to grow and multiply, while also maintaining their ability to differentiate appropriately when needed.

In vitro conditions have to be carefully controlled to mimic the natural environment of stem cells, including the use of specific growth factors, nutrients, and signaling molecules that guide the cells' behavior. While proliferation is typically desirable to generate a sufficient quantity of cells for research or therapy, differentiation must be tightly controlled to produce the specific cell types needed for treatment. Optimizing these conditions is a critical aspect of regenerative medicine, as it enables the creation of a reliable supply of specific cell types for transplantation.